First, when you become a foster child it will be a little different. But, on the other hand it will be quite easy to meet a new family. For example, when I first became a foster child, I was so afraid that she would not like me. But, however, she really was gentle and loving, and I stayed with her for two years.
Most important, some foster parents have really strict rules. Such as, ask before you go out; be in the house before dark, and they have to know where you are and whom you are with. Also, they have other very common rules like, clean what you mess up, no eating in the rooms, etc. They do this because they care about you as you were their real children and they don't want anything to happen to you.
However, foster parents also look at how messy or neat you are. Such as if you keep your room clean, or do you clean after yourself. They prepare you for independent living. So that’s why they will be always on your back about things.