I'm not really good with tutorials, so if you have questions you can just comment.
Step 1. Well, I drew the head only because that's what I start off drawing with, but that's not important. Instead of having the breasts be just circular, make them more oval, like an egg or lemon. Draw guidelines for the breasts and shoulders. The shoulders you be somewhat rounded and the collar bones chould go with the direction of the shoulders, or else they'll look a little off.
Step 2. Stomach time! This is one of the hardest parts, because there are a lot of curve lines that need to be exact. At the end of the oval line, start curving down to make the stomach. In order to be exact, add some circles to see where the stomach lines will be. Also, start making her hips. For the hips, draw impossible curves, and then add some lining, which is her back. Also add her humerus (the top half of her arm) and elbow. Make the elbow pointing out a bit, to make it look more like a real arm. Tip: If you're doing this traditionally, make the guidelines even lighter than the sketch, so erasing will be easy. But you probably know that already....
Step 3: Leg time! Since this is only half body, I'll only draw the thighs. From the bottom of the stomach, draw 2 curved lines showing where her leg starts. From the inner part of the curved line, start drawing the legs down. Before you do that though, draw 2 circles for where her butt should be. xD (I didn't draw it in the tutorial, though) Then you start drawing the legs curving down. If you want the 2nd/3rd dimensional effect, draw a curved line where the front of her thighs should be. Also, add the bottom of her arm and do whatver the hell you want with it, XD.
Step 4: Erase guidelines. I Don't need to explain this, it's that simple.....
Step 5: Add detail! I didn't add much detail but you can....
and, TA DA! You've got yourself one sexy ladayyyyy
many thanks