Just in one page I've seen a big leap in skill, nicely done! The last posts especially. Regarding the last post specifically... it's alright if your image doesn't match a reference exactly. In fact, I think it's better sometimes when they don't. You can exaggerate more in the gesture and emotion in the figure when you draw beyond the reference. It's still only a flat, 2d image, and sometimes the best artists are set apart from the rest when they add that extra soul into their picture themselves through acquired skill :] Otherwise, copying a photo inch by inch risks a flat looking result... which I've only just recently started noticing myself.
When studying anatomy from an image that's a little different, since you definitely want to know exactly what's going on with each physical aspect of the figure.
I ramble a little :] I really like that last image, and that you thought to make a comparison like that.
I adore Suicide Girls as well, and I've been itching to use them for reference and color studies too. I just haven't gotten around to subscribing quite yet :] Nice to see that someone else has the same ideas!