Here is the first one I would get:
http://www.miqdma.com/flyer.pdf
and another
http://www.northcountrywhitetails.com/
These two have alot of good information in them, I own them both. I have quite a few books on plotting, but these two are what I would start with. The QDMA website has forums on it also, and a forum just for plotting, tons of good info there. That link is:
http://www.qdmaforums.com/
Good luck. And another thing, be sure and fertilize your plots, it helps alot.