I am going to begin this tutorial by addressing one of the most common requests
The main problems people seem to have with drawing breasts are the shape and the placement. A lot of artists (professionals as well as amatuers) make them look like balloons that have been taped onto the subject's chest; this is hardly a natural look. If you look through figure drawing books, you'll see that they are more like halves of a sphere or overturned teacups rather than balloons.