Before I was thrown headlong into WWG land I dabbled in graphic illustration, so I understand the issues
If you have the time and money I would HIGHLY recommend taking a sketching/anatomy course (nude models). There is really no better way to understand the human form and if your instructor is good they'll cover the whole range of techniques and perspective issues.
If that's not possible the single best book I've found on the subject is "Drawing on the Right Side of the Brain": http://www.amazon.com/New-Drawing-Right ... 0874774241 . I give high marks to this one because it covers almost everything I learned in my drawing class in college and the techniques are rock solid.