Invest in Collin Moshmann's book >> SNG Strategy. It'll be a huge help I guarantee it & is well worth the cost of the book.
I've also read some excellent SNG articles (not your typical beginner/intermed. stuff but more advanced).. & prior to doing so was basically a break-even SNG player. After reading the articles & Moshmann's book I found my results improved dramatically (was on a run for awhile with ROI 20%+ but then closer to +10% in the longrun).
I've never heard one single player say they felt they wasted their money on this book.
Checking out some good SNG training vids. would be the next step beyond this (imo). I'm not talking about crap stuff like MartySmith/Turtleknife stuff... I'm referring to good vids. put out by good coaches (winning players). It is well worth the investment.
Brad Booth - > "Like a fight... it's not how you start, it's how you finish"