My friend is obsessed with Moana, so for her birthday, I did up a design based on some shirts I saw on the internet. (I cannot take credit for the design, neither will I sell them, since they are not my work).
This design was six different colors. Hence, six different layers. Pretty tricky to line up. This is also about when I began to realize that the heat transfer vinyl shrinks a little when applied, so that subsequent layers don't quite line up. Not so problematic with this design, but extremely frustrating with a couple recent designs I've done (which have a thin and detailed black outline that overlays the color layers... lots of trial and error and adjusting and wasting vinyl.)