If you didnt see the excellent series screened on Channel 4 last week - Life Class: Today's Nude I recommend catching up with it on their website and having a go at some drawing. It is quite a good bridge between working from photos and a real life class despite the fact its still two dimensional. The slight pressure of getting the information down quickly was real enough and there are some good nuggets of info from the artists demonstrating. Life drawing is a great leveller and I found some of the professionals results suprisingly encouraging!!!!
These are my efforts, anything from 5 - 20 minutes I reckon. Go on, give it a go.