Hi all. Not new to archery, but new to owning my own bow. I hope this question isn't too silly. What is the formula for selecting the propper arrow length when getting new arrows? I just bought a PSE Nova compound bow. The draw weight is set at 70, with a 28 inch draw length. There is no overdraw bar on the bow. For the now I will only be target shooting using feild tip arrows and using a release. Thanks in advance for your help.