Keep your eyes open for the first signs of the rut, because the pre-rut is one of the best times to bag a buck.
The first rubs signal that bucks are getting interested but are not yet quite all the way "there." At that period, buck grunts work well, but keep your calling subdued. Rubbing your rattling antlers on trees and just lightly "tickling" them is the best way to rattle early on.
As the pre-rut advances, you can try being more aggressive in your grunting and rattling and maybe even simulate a full-scale buck fight. Adding doe beats is a good idea. What you are trying to accomplish is staying in synch with the natural progression of buck behavior during the pre-rut. Simulating behavior and sounds that are not normal for a particular time of year will most often do more harm than good.