I have a good friend who likes to decorate her kids rooms as gender neutral so that she doesn't have to redecorate for each child that is born. If you are very practical like my friends is, you may be interested in doing the same thing.
Below are some different color schemes that can be used for either a boy or girl.
Green + White
Turquoise + Yellow
Green + Turquoise + Burnt Orange
Yellow + Grey
These pictures really just scratch the surface, I found so many different examples that I could have used in this post. Hopefully, these ideas get your wheels turning if you don't know where to start:)