First thing is to take some art classes, learn some basics about proportion, color, value, etc. After that, start developing basic croquis (a figure ~10 heads tall) that you’ll use as a template for clothing. Realize, though, that fashion illustration has nothing to do with actual designing. To learn how to make clothes, you’ll need basic construction skills (hand sewing, machine sewing) and learn how to draft patterns and create toiles.
Start working, building a portfolio, and practicing. Depending on whether you want to illustrate or design or photograph, you’ll want to hone those skills and try and get work as an assistant/intern/whatever.posted about 5 years ago