From that last batch of children's book illustrations last semester I've settled on a process of sorts- it's still fairly haphazard and changes in slight ways for each picture, but it's incredibly nice to feel this sort of security. I start with colored lineart, do a series of differently colored inkwashes, build onto that with watercolor and marker, and then go to town with colored pencil and gouache. Here's a couple progress shots illustrating the process, followed by a small gif:
And that's that! :]