A newbie who wants some advice

Hey, emm, I'm NessyNoinex and yesterday I discovered this wonderful site. I hope I can learn a lot from here, I've already seen a lot of useful advice and I want to practice them.
(Well, first of all I should say that I'm not English of birth so maybe I can commit errors without noticing. Anyway, you can point them, it will help me to correct them).
Well, let's go back to the prior problem: I suck at drawing bodies. I just draw "adventure time" bodies, which I don't really like because I want to improve and draw more realistic ones. So I started with this practice tool to draw figures but... I don't want to see nude models, but if I look at the ""decent" models", I feel like I'm not going to improve because their bodies are covered with clothes .
What do you thing is best for me? Try to sketch nude models or try other ways?
Thank you everyone.

Nude models are best for learning anatomy, however if you're uncomfortable looking at photos of real nude people, you may learn better from an artist's book on anatomy. I don't really think you'll get a good grasp of it by looking at clothed people. You need to understand what's underneath to learn how to properly place the clothing, anyhow.
This book might help you: http://www.scribd.com/doc/4437416/loomisfiguredraw