frasettor,
If you are only hunting deer, then start at your low weight field tips.
If you intend to hunt something a little heavier skinned, then I (my opinion only) would start at around 145 grains, and work up.
I believe that the heaviest tip you can get good arrow flight out of, is the best one you can use.
Once you have found which weight flies best from your bow, then you need to work on tuning your broadheads of that same weight, to get the best flight from them.
You may need to try some different spine weight arrows, too.