Hitchhiking is very common in Israel. Hitchhiking is done by pointing to the ground with the hand far from the body, instead of raising a thumb.
The most usual way to start an hitchiking journey is to take a bus out of town, to a junction in your direction. Almost every junction has a hitchiking spot (the famous Trempiyada), or atleast a bus station where drivers can stop. It is very hard to hitchike from the cities themselves, and inter-urban buses are relativly cheap and can get you to the nearest junction.
Safety
Like always, precaution is needed when hitchiking, although in Israel hitchhiking is a way of life. You will find hitchhikers everywhere. Your best bet for getting a safe ride in Israel is getting into a car with people who know what they are doing. Even still, caution is necessary.