Life Drawing Classes!

[Ngaire Winwood]

I had a look through the searches and couldn't find appropriate information. My question, for portrait poses from a model, how long are the sessions (20 minutes?) and what poses, lighting is best? How would I arrange, say, a 4 hour session?

I had read the threads here and also photographing section, but is there certain principles to allow the models to promote better features to draw and paint from? From experienced models to people off the street? What paperwork do I need for them to sign before I can draw them?

If it is at night, what is the best possible lighting to have ceiling lighting or is it best to have mobile lighting to produce better drawing/paintings (rembrandt lighting)? I agree that natural lighting is best, but for life classes this is not totally suitable. Any suggestions?