Great! I'm going to answer the five most important questions you'll ask yourself, if it's your first time in the country:
1. Is Israel really safe?
How exciting - you booked your first trip to israel. But if you tell your friends about your plans, you'll probably get the classic reply: "Israel? Isn't that dangerous?" Not at all, as a vacation destination I'd say it's not more dangerous than any south-European countries. Myself, I feel more safe in Tel Aviv than big German cities, also when I'm walking alone at night. Just the central bus station ("tahana merkazit") isn't really pretty and I wouldn't go there all by myself in the night - for the ones who know Berlin, it's kind of the Israeli version of Kotti, just more floors and a bit more confusing.
But you'll find security all over and to enter shopping malls (and even tahana merkazit) you'll pass a guarded gate and get your bags checked.
Rocket alarm is still also a thing, unfortunately, but if you're visiting the common tourist places, you're pretty safe. Here's a link to a twitter account that is tracking all the red alerts, the rocket alarms and the places affected. So even if it looks really dangerus in the news, you can check and compair your traveling route with the areas.
In case of an alarm you should get to the most protected area in the house, most new buildings have a bunker, but if not you can be safe in the stairwell, or a room far from windows, and even stay there for a few minutes after the alarm ended. In public places you can just follow the Israelis, tehy will know best what to do in such a situation.
2. Is the questioning at the airport really that bad?
From "quickly and uncomplicated" to "extremely suspicious" - I passed the security checks in any possible way. And I still say: If you consider it's also about your security, all the questioning is half as bad.
Depending on the airline, there are already questionings in your home country: What's the purpose of your visit? Have you been to Israel before? Why do you travel to Israel? Do you know anyone in the country or in other countries in the Middle East? So not really anything to be worried about.
The same, or similar questions are asked again after landing, when your passport gets checked and you get a little blue card - they hand these out instead of stamps, take care of it and don't throw it away, in hotels for example it's proving that you are a tourist and don't need to pay the 17% extra, like Israeli citizens.
When you're leaving the country there's another questioning, also why you travelled to Israel or if you got gifts or something to transport for somebody else. Sometimes the questions become more detailed, it happened to me because I travelled alone, but also simply for training purposes - they see you have some hours left before your flight, so it's a good opportunity to practice. But if you're really honest and have nothing to hide it's half as bad.
3. How do I get from the Airport to...
Jerusalem: Weekdays (take care, it's Sunday to Thursday!) by train, the train station, Itzhak Navon is next to the central bus station with all the important connections inside of Jerusalem, as well as the light rail. Tel Aviv: There's a bus that leaves the airport every full hour, Along the beach of Tel Aviv all the way up to Riding. It's working 24 hours a day, except for Shabbat (Friday 17:00 to Saturday 21:00).
Second option is to take the train, you have 4 train stations in Tel Aviv. The Train (last stop Nahariya) leaves around every 30 minutes and will cost roughly 15 Shekels.
Haifa: By train, every half hour. Its last stop is Nahariya, the the train ride itself will take about an hour and a half and is one of my favorites, along the coast of the Mediterranean.
On Shabbat there are sheruts, small busses to Jerusalem an Haifa, they seat 10 people and leave when they're full. The sheruts wait in front of the main exit of the airport, you can't miss them.
To ride a bus inside the cities you need a "Rav Kav" and can't pay with cash anymore. You can get it at the airport or on almost all kiosks around the country, and also charge it there.
Every time you charge your Rav Kav, you'll get 20% of the amount you paid as a bonus on top. You can find all details here.
Take care, daily passes aren't valid for 24 hours, but just until the end of service, which is around midnight or 1 AM. Monthly passes are valid for 30 days from the date of purchase.
4. How is it to drive myself?
It took me some time to get used to Israeli drivers, but if you're driving defensive and carefully, you'll be fine.
When traveling, we always booked a rental car from our home country, but it's also possible after your arrival. You need is an international driver's license, and cars that you rented at Israeli places aren't insured in the West Bank, so take care where you're going. It's fine though to drive on route 1 from Jerusalem to the Dead Sea, or on route 90 to Beit Shean, but just skip the visit in Jericho.
Outside of the cities you can go 90 km/h, on route 6 and other designated highways you can go 100 km/h.
I love to discover Israel by car, but again, be really careful, because some basic traffic rules seem to be considered just a suggestion.
Besides the Carmel tunnels in Haifa, Route 6 is the only road that you need to pay to use. The amount will be charged automatically and you'll later get a bill from the rental company.
5. Do I need shekels?
It's not really necessary to change money at home, also avoid the expensive changing booths in the airport. You can pay almost everywhere with credit card. In the cities there are a lot of changing booths, just compare them, before you change your money.
If you want to withdraw money, it works on almost any bank machines or at the counter, there you'll just also need your passport as an identification.
Also make sure to remember the PIN of your credit card, you'll need to type it in for purchases of 300 shekels or more.