It is true that new ideas these days are so interesting. Some parents may come up with a specific theme as if preparing their child for their future career from Day 1. However, let us just be realistic here: he or she is still a baby. The safest choice is the classic style, like the color of the wall that is not too babyish (for example, baby blue, baby pink, or even bright yellow or green.)
This will be useful, especially if you plan to make it as your child’s room when he or she grows up. Use some removable accessories like wall decals. Regarding the wall paint, make sure the material is toxic-free (water-based paint or non-VOC), and the room itself has good ventilation.