San Francisco and California are popular travel destinations. Rightly so – the region is beautiful. Since I started as Silicon Valley correspondent for Handelsblatt, our family has had a steady stream of visitors. Friends and colleagues from Germany and across Europe regularly come through, and we keep getting the same questions. So I've collected the most useful pointers below – the things you usually don't find in a guidebook. Almost all of these tips apply equally to visitors from anywhere in Europe, not just Germany.

Preparation and entry

A few simple tricks ahead of time can save a lot of effort. The following items are the ones we keep passing on.

Tip 1: Book a direct flight to SFO if you can

If you are travelling to San Francisco or Silicon Valley, you will most likely arrive by air. The very first tip is to book a direct flight to San Francisco International (SFO) wherever possible. Connecting flights – especially when the first stop is somewhere else in the US, such as Seattle or New York – often cause problems. In many cases you have to collect your luggage at your first US airport and re-check it. That can eat up a lot of time and put your onward connection at risk.

Tip 2: Be ready for long waits at the border

After landing at SFO, expect a wait. Queues at passport control can be long; one to two hours is not unusual. The only practical advice: get in line as quickly as possible after landing – and use the bathroom on the plane rather than after.

Tip 3: For frequent travellers, Global Entry can pay off

If you travel to the US often, there is a way to skip those queues. The US offers an enhanced security clearance called Global Entry. It currently costs 100 dollars and is valid for five years. The application process takes several months and the eligibility requirements are relatively strict, depending on your visa or status. More on the programme at the Department of Homeland Security.

Tip 4: No fruit in your bag – check the import rules

The US has very specific rules about what you can bring in. California is particularly strict. It pays to look up the latest rules. Officers at the airport – sometimes with sniffer dogs – will check, and undeclared fruit can mean stiff fines. The reason: California protects its many rare plants and animals from invasive pests. The official rules are here: cbp.gov/travel.

Arriving in San Francisco

By the time you land in San Francisco, you are usually already exhausted. Twelve hours or more on a plane, and the time difference of nine hours from Central Europe (eight from the UK) hits hard. These tips help with arrival.

Tip 5: Free Wi-Fi the moment you step off the plane

San Francisco airport offers free Wi-Fi in all terminals – no registration required. The network is called #SFO FREE WIFI. Useful if you need to coordinate with friends or colleagues on the ground straight away – for example, to settle on a meeting time.

Tip 6: From the airport into the city

SFO is connected to San Francisco and the rest of the Bay Area by the regional rail system, BART. You can buy a ticket directly at the machine. Depending on the time of day, the wait between trains can be relatively long. Alternatives: taxis and ride-share services like Uber and Lyft.

Tip 7: Uber and Lyft pickup at SFO is hidden

Taxis at the airport are easy to find right outside the exits. Uber and Lyft, by contrast, can only pick up passengers at a specific designated zone. It pays to look the location up beforehand. The airport publishes its own guide to the pickup spots.

Tip 8: Public transport in San Francisco is worth using

By US standards, San Francisco and the wider Bay Area have solid public transit. If you are moving inside the city, the trams and the metro work reasonably well. The bus network is okay-ish but chronically unreliable. We mostly take buses when we don't have to change. With buses, the rule is: there are timetables, but the buses almost never run on time. Better: use map services like Google Maps for bus journeys; they show the real-time positions of the buses.

Tip 9: How the Clipper card works

You can buy a single bus or metro ticket on board, but it's better to get a Clipper card. It's a plastic card you can top up with cash or a Mastercard/Visa. The machines aren't at every stop – only in the city centre and at BART stations. The Clipper card also works for the regional BART trains. Instead of the standard three dollars per ride within San Francisco, it's only 2.50 dollars. Passengers under 19 ride for free. Unlike most German transit systems, a ticket is valid for 120 minutes regardless of the route – so you can travel somewhere and back within two hours for just 2.50 dollars per Clipper card. If you're moving around a lot in one day, a 5-dollar day pass kicks in automatically. The only exceptions are special services like ferries or historic rail lines. Fare overview at the local Muni network: sfmta.com.

Tip 10: Accommodation in San Francisco – often expensive and cold

San Francisco is expensive. Very. That can't be repeated often enough. Plan accommodation early. Winters in San Francisco are mild, which has led many property owners to skip insulation altogether. Be ready for the possibility of a hotel room with single-glazed, draughty windows. Read reviews carefully. We have seen friends offered space heaters because the regular heating couldn't compensate for how draughty the room was.

Tip 11: Pay attention to safety

People arriving from Europe often can't quite picture the safety situation in San Francisco. We have witnessed several car break-ins. Some parts of the city involve a lot of unpleasant interactions. Look up the lay of the land beforehand. The city offers a crime map: crimemapping.com.

Mobile and finance

Two areas where lack of preparation can become genuinely expensive: mobile data and payments. Mobile in the US is much more expensive than in Europe. A few tricks help avoid high bills. The same applies to making sure you can actually pay for things on the ground.

Tip 12: Local US SIM cards are often very expensive

The classic travel tip in many countries is to just buy a local SIM and avoid roaming charges. In the US, this only partly applies. The three big carriers – Verizon, AT&T and T-Mobile US – often charge eye-watering prices for their plans. The true cost is often hidden in the fine print. One example: friends of ours signed up for what looked like a one-month bargain mobile-data plan with T-Mobile US and ended up paying 60 dollars, because many of the actual fees were hidden.

Tip 13: Roaming with your home plan can be the best option

Depending on your home tariff, the best option may be to add a US data package from your home European carrier. It's not cheap either, but it can work out cheaper than an over-priced US SIM, and it avoids the setup hassle.

Tip 14: Check that your phone actually works in the US

Mobile networks work similarly all over the world. Carriers use specific frequencies to connect to phones. The exact frequency spectrum, however, can differ. Between Europe and the US there are some material differences. That can mean a phone bought in Europe gets poor reception or doesn't work at all in some US areas. You can check this in advance. Most carriers offer a way to test your phone's identifier (IMEI) ahead of time. T-Mobile US has a test page; Verizon has a similar one. AT&T's process is currently slightly more complicated.

Tip 15: eSIMs offer cheap data plans

A good alternative is the eSIM. You can use a mobile data plan without inserting a physical card into your phone. A number of younger mobile companies use the technology to offer low-cost travel plans. First, check whether your phone supports eSIM. One provider that friends of ours have had good experience with is Airalo: airalo.com.

Tip 16: Disable call forwarding (e.g. to voicemail)

Depending on your tariff, voicemail can become a cost trap on a US trip. Many carriers charge international fees for any call forwarding – including to voicemail – when you are abroad. To be safe, switch off voicemail forwarding for the time you are in the US.

Tip 17: Wi-Fi calling can be a cost trap

Wi-Fi calling is a great innovation in principle. When mobile reception is poor, the call simply runs over Wi-Fi. Inside Germany, those calls are billed like ordinary calls. Abroad it's different – they are not covered by EU roaming rules. So providers handle Wi-Fi calls in the US differently. Check beforehand exactly how your provider charges Wi-Fi calls in the US, or simply switch the feature off for the trip.

Tip 18: Bring a proper credit card

In Germany, credit cards are often unnecessary. Debit cards (EC cards) work well in shops. In the US, credit cards are the standard. Many places – car rental counters, hotel check-in – require a real credit card with a credit line, not a debit card that simply charges your account immediately. Many European banks now offer cards labelled as "credit cards" that are actually debit cards. That can cause problems with US car rental firms or hotels. Check carefully in advance that you really have a proper credit card. Visitors from the UK and other European countries should check the same.

Rental cars and insurance

Even though Bay Area public transit is better than in many other parts of the US, many trips simply don't work without a car. A rental car is often unavoidable.

Tip 19: Get to know the differences in driving rules

US road rules are broadly similar to European ones. The adjustment doesn't take long. But there are a few differences to keep in mind. For example, right-on-red is allowed at many intersections. People also pass on the right on the freeway. The German automobile association ADAC keeps a useful overview of the rules (in German). For UK drivers, remember: driving is on the right.

Tip 20: Watch out – rental cars often lack liability insurance

European drivers are used to rental companies trying to upsell unnecessary insurance, but with the essentials always included. In California, that's not always the case. We have seen, several times – both ourselves and through friends – that liability insurance was missing from the included rate. As in Europe, liability insurance for cars is, in principle, mandatory. But rental companies often use a legal loophole to leave it out of the headline rate. For US citizens that is sometimes not a problem: if they own a car with their own liability cover, that often extends to rentals. As a European visitor, you don't get that benefit. Check carefully whether your rental rate includes liability insurance.

Tip 21: Book your rental car from Europe

In our experience, rental car prices booked from Europe are noticeably cheaper than on-the-spot rates in the US. European comparison portals like check24.de or billiger-mietwagen.de are good starting points; UK readers can use Kayak or similar.

Tip 22: Have any pre-existing damage documented before you drive off

Rental cars often have damage that hasn't yet been recorded in the contract. We have repeatedly heard stories where big rental firms refused to add new damage to the contract – the staff member's response was simply: "just take a few photos of the car." On return, that often becomes a problem – the rental firm may say the photos don't clearly show the existing damage, or that they aren't sure the photos really pre-date your use of the car. So the only advice is: be persistent, and have all damage formally documented at the rental desk in writing.

Tip 23: Don't, really don't leave anything visible in the car

It is genuinely surprising how often cars are broken into in San Francisco. Smashed window glass on the streets is a daily sight. We have witnessed several break-ins ourselves. Thieves don't only strike when they see something obviously valuable – sometimes a jacket on the seat is enough. There is little protection against this. The only piece of advice that holds: don't leave anything visible in the car. Anything.

Tip 24: Check your travel health insurance

The US healthcare system is very expensive. Even a basic doctor's visit costs a lot. Good travel health insurance is therefore essential. Sadly – and we know this from direct family experience – supposedly good European travel-health policies can turn out to be a serious disappointment when costs go up. Read the fine print on coverage limits and exclusions before you go.

Sights and the right clothes

The Bay Area, and San Francisco in particular, has a rich cultural programme. Museums and venues are in every guidebook. A few addresses help you find interesting places off the standard routes.

Tip 25: Free events in San Francisco

The Funcheap platform curates a detailed programme for San Francisco and the wider Bay Area. Many ideas for worthwhile day trips and evening events: sf.funcheap.com.

Tip 26: Pack for any weather

Many Europeans underestimate how cold San Francisco can be. The city is famous for its microclimate. While it can be bitterly cold and windy on the Pacific beaches, the financial district downtown can be in glorious sunshine at the same time. We always tell our visitors to pack for everything. From t-shirt weather to chilly fog within minutes is normal.

Tip 27: Visiting tech-company campuses – Google is open, Apple is closed off

Silicon Valley is home to many of the world's most valuable tech companies. If you are interested, a campus visit is worthwhile. Google parent Alphabet is relatively open. The campus is accessible, and you can take photos almost anywhere. The new Bay View campus is particularly impressive. To enter one of the buildings, you need a Googler to invite you in.

The opposite model is iPhone-maker Apple. Founder Steve Jobs designed the gigantic Apple Park complex. From the air, the ring-shaped building looks like a huge "O". The whole site, however, is closed off. From the pedestrian path you can't even see the building. The only accessible area is an Apple Store outside the main complex.