I get asked this often. Well, the less important part of the answer is Illustrator, but do pick up one of the non-evil alternatives.

The more important part of the answer is how you intend to do it. Analog/Digital? Tablet/Mouse? Freestyle/Accurate? It comes down to whatever you’re comfortable with. And practice, I suppose.

The video capture demonstrates Digital, Accurate and Mouse with my putting-together of Anne Boonchuy from the upcoming Disney series, Amphibia as a vector model. From her hair, to her head, torso, arms, and legs, applying my own preferred limb thickness and body shape.

Star Butterfly was made the same way. Gather refs of the character you wish to draw. Have a look at how they’re posed in the show. Have a feel of how their body parts are put together and animated. How would you draw them if you had to take their body apart? 

Once you have an idea of how they appear, look for other refs to pose them. Trace art if you really need to until lines feels right. Get a feel of the linework and shapes. Then keep drawing without them. And do it on your own terms. Have fun with it. Don’t feel like your stuff is inferior, especially if you just started.