I'm not a big fan of
www.ar15.com but there is a REALLY good guide on building an aR15. Pretty darn complete. I've used it twice when I first started building them. All of my kits come from
www.model1sales.com and
www.m-aparts.com.
Here's a link to the guide on AR15.com Props to user "FALARAK" for putting this together.
http://www.ar15.com/forums/topic.html?b=3&f=4&t=226782