All good advice so far, here's a little more. If you are putting a scope on it, it's real important that your horizontal xhair is parallel to the limbs, which will make your verticle hair perpendicular to the limbs. That's the rascal you need to keep from having grief at farther ranges later on. I have levels installed on my bows risers, but you can do this w/ a common "torpedo" level.Have scope still loose enough to move but not sloppy loose. After you put the scope on and adjust your eye relief, you hang a plumb bob at 20 yds, put the torpedo level across your rail and while watching bubble in level, align the verticle hair to string on plumb bob. Sand bags help alot! Tighten rings gradually and equally on each side and recheck the above. Failure to accomplish this in any fashion, whether my method or any other, will result in dead on at 20 and a tad left or right at farther ranges w/ the error growing w/ the increased range.

Cheap sand bags: Doubled up "gallon zip-locks" filled half full of sand, get all the air out that you can, then put them in old cotton socks, tie knot in end.