First session after a 6 month drawing break (house renovation). Rusty as an old nail... 

I find that coming back from a break is a great time to change or add to how you do things. It's less intimidating to me to experiment when I'm still kind of crud, because the "failure" stage is less frustrating than when I can compare it to me at my best. You seem to have a strong understanding of the ribcage and pelvis, so maybe now is the time to really study legs or muscles or whatever you want! Proko on YouTube has a pretty extensive anatomy series, and one of his videos might make a good starting place.

Thanks Retrodictionary! Yes, I also feel that I progress in steps, after each break. When I come back to drawing I have maybe forgotten some bad habits, and can see things with fresh eyes. That is the justification I allow myself at least ;)

I am most comfortable with the pelvis and torso. Or the Bean as Proko refers to it as ;) (I have done a few of his classes). Legs and arms have really been a pain for me. I can't seem to fully wrap my head around how they bow, swing, flow, bulge. There are so many subtle shapes/curves that, if you get them wrong just a bit, it throws everything off. They're so different from model to model as well :P