I just buy what I like for colors and then for a theme for who I will eventually will make quilts for. I like going with "themes" and the hobby/interest that the person has that I want to make it for. I am not a traditional triangle etc designs. Fine if you want to sell them but I make them for my family and friends. Eventually you will make a baby quilt so get male colors and female colors for that. Themes are great.
But u might want to go with colors that go together.
Hope this is helpful.
Eisgoow