We’re going to do something similar, making a Halloween dress-up doll with various complete costumes broken down into parts that you can mix-and-match to create custom costumes for the character.
You can do all of your drawings in Flash if you’re more comfortable with creating artwork from scratch in Flash, but you’ll still want to follow along as many of these basic principles covered will still apply. I’ll be working in Photoshop because tablet-drawing in Flash drives me batty, but you can use any graphics program of your choice, provided that it can export transparent GIFs or transparent PNGs.
I’ve started off by drawing my basic character in pencil, decently covered (no nudes, thank you), then scanning it into Photoshop, layering detailed color on top of it, and cleaning out all of the white space around it so that she’s free-floating with no background. (For more on graphics software, working with color and exporting images with transparency, check out Guide Sue Chastain’s enormous library of lessons on graphics software.)