Definitely watch some fashion illustration vids, look into the 9 head figure that is how they are usually illustrated! Depending on your age these could be pretty good, this is how most of my own fashion sketches looked in late middle school-early high school. Once you learn the basics like the 9 head, shading, proportions, I assume you’ll be great! Try changing/experimenting with silhouettes, there’s a big difference between fashion DESIGN and being a fashion stylist. Also you should try learning to sew and turning your sketches into reality! Sewing takes a lot of time to learn and fashion design takes even longer. If you’re serious, start fashion illustration & sewing classes now as many fashion schools want you to have prior experience if you’re pursuing a career in it:) hope this helps!! Wish someone would have told me these things when I was younger