Pat's recommendation on reading material is seconded by me. The book is must reading for the AR fan.
I'll also take this opportunity to second Sgt. Carlin's advice on free floating the barrel and other sage advice. That's one of the most important thing to do on a competition AR. Put some good sights on (NM quality) and a new front sight blade. A good trigger job.
There's more in the book but you'll have to read it yourself and judge for yourself. Good shooting.