As you all know, I have two boys. Their ages are 3 and 1 year. When it comes to the design of a kid(s) room you have to think of the aesthetics of a kid. Adventure, Color Identification, Simple shapes.
The walls in my kids room have nothing on them but paint. For $2.00 of felt fabric and some time. I made some graphic organic art for their walls. You can do this too. All you need is
-a stick from your yard.
-an outline of a bird (copy it from the Internet)
-whatever color felt you want
-pillow stuffing ( or old socks)
-Cup hooks (for hanging the stick on the wall)