This isn't really off season advice, but it's my very best advice in general for killing whitetail bucks. It is not easy for most people, but sitting ALL DAY, from dark to dark, during the rut is the single most effective way to kill a buck. I have lots of trail cam pics to back up this point.
Do the drill in the video Bryan posted, it is awesome. Another one that is more fun is to get up in a treestand with your bow and a bunch of arrows, wearing your heavy hunting clothes. Close your eyes and have a buddy throw a cube target or Reinhart 18-1 target, and you open your eyes and quickly shoot it where it lies, no rangefinder. You have to shoot around branches, behind the tree, steep downhill, whatever presents itself. It is very humbling at first and you'll likely be surprised how horrible you do. But it will drive home the fact that realistic practice is invaluable compared to shooting in a tee shirt on level ground at known ranges.
That's a good idea ruck. I may just have to try that! I am also due to replace all of my ratchet straps on my tree stands this year
