Depends what you want to do, for actually using P5 to make scenes the included manual is actually pretty good - playing while using the manual for reference is enough to figure most things out. Dr Geeps tutorials are about the most comprehensive source of information on the web and there are lots of other good ones here and at Daz. If you actually want to make custom props and figures and set them up for use in poser the best book is 'Secrets of Figure Creation With Poser 5' by B L Render (0240519299)