I've heard of a few different things but not sure what would be the best? I'm still a beginner with just 1 year experience and this will be on my garage wall via some plywood. It is a 3-section bag. I've heard: tossed sand grain (aquarium tank type), mung beans, rice or plastic beads. Any suggestions on which one? Also, when I'm putting my wall bag up, being that I'm 6'7", should I have the top of the 3 sections eye level and the middle second below that? There's not many people who I'd be punching in the face my height. lol Thanks!