The answer is actually pretty complex. You learn to draw and you will learn to draw people. Drawing on the Right Side of the Brain by Betty Edwards is a good place to start, as mentioned above. Go to your library and talk to the librarian about it. If they don’t have it they can get it through inter-library loan. I also recommend, strongly, Kimon Nikolaides’s The Natural Way to Draw. Again. Go to the library and talk to your librarian about it. If either book is useful to you, then save your pennies and buy it. You will probably be using it for decades, like the rest of us.
Meanwhile, this is not a solution but it’s a help with lots of pointers about figure drawings:
http://drawinglab.evansville.edu
Have fun.
When drawing clothes, draw them to drape similarly to how they are worn. Learn about fashion and clothing design sketches in this free video from a fashion designer.
Learn how to surf from Designer Yigal Azrouel. Watch him walk through his collection and describe how he created a dress, a scarf, a motorcycle jacket, and more. Drue Kataoka talks with Yigal Azrouel. Learn about the inspiration behind his collections.