One of our favorite ways to decorate is to start with a white canvas. We find this works particularly well for childrens' spaces because many childrens' furnishings and accessories are saturated with color.
If you start with a white canvas, you can build in color with furniture, toys, and textiles and the good news is that almost anything goes. You won't need to worry about staying within a color scheme. The photos of this house in Sweden found at Emmas Design Blogg illustrates this concept beautifully. Images: emmas designblogg