There has been a lot of conversation about RGB vs. CMYK colors, separations etc. in this forum (and elsewhere too). I found a very good article about most of the things anybody should know before even start to work with material that is qoing to be printed....
http://www.smashingmagazine.com/2009/10/27/10-pre-press-tips-for-perfect-print-publishing/
Haha! The comments are pretty entertaining. Funny how many people won't budge out of their comfort zone, even when it's clearly obsolete. Others just have reading comprehension problems.