Get Byron Ferguson's book "Become the Arrow" and Ricky Welch's video "Instinctive Archery, Volume II". You can't follow both exactly, because they have different styles, but both will help.

Shooting 3-under will give you a lower point of impact if you use the arrow as a referance, but otherwise it should cause no adverse effects, other than possibly a noisier bow. Chek-Mate did some testing--had a "pro" shooter shoot a bow tillered for split, 3-under, and even reverse tillered (tillered for 3-under, but upside down) and there was no change in accuracy, just bow noise.

I know, and have seen, guys that are VERY accurate--some shoot split, some shoot 3-under.

Chad