One of our members wrote a great
Photoshop Basics Tutorial a while ago, that covers layers, layer styles, filters, channels, and a few other useful Photoshop techniques. Another member has written a
Soft Style CG Tutorial, and I'm working on a cel style one now, all of which will end up in the guild e-zine at the start of Feb.
As for lineart... I usually ink my sketches with a very thin felt tip pen, erase the pencil lines, scan at about 400dpi, then increase Brightness and Contrast until it looks fairly clean. I've found that it works pretty well, just have to go in with an eraser for the bits where I've pressed to hard and erased and redrawn too many times
sweatdrop A lot of pro illustrators use the Pen tool for lineart (depending on the style of the illustration), but I find it really hard to use most of the time.