I recommend a flat white ceiling and I personally like a pastel type of mild color for the walls. A light pastel green is relaxing and peaceful, that is to me anyway.
Now if you really want to know how to paint your bedroom walls up really in an awesome way, it is to add a star mural to the walls and ceiling.
You won’t see it during the daytime. It is when you go to bed and turn the lights out that the fun begins. All the sudden it looks like your walls and ceiling have disappeared and your bed is in outer space!
Most people prefer just a nice star mural on their ceiling but if you want a cool 3-d effect that makes it all more dramatic you can go with the walls as well.
If you are interested in knowing more check out this site: http://star-mural.com