If you aren't carrying anyone than more than say 8 lbs., almost anyhting will do. You don't need a waistbelt to carry the load, or a suspension system to help you.
But, if you need to carry any more weight, then something that fits, and is comfortable under load is a must.
The way most pack makers determine this is by using one's torso lenth - basically the distance between the base of the neck and the flat spot at the end of the spine.
So, find a design that is made in your torso lenth and try it out under load. Any decent shop that sells packs should be able to allow you to do this.
Keep in mind that we hunters sometimes carry alot of gear depending on where, when and what we hunt. Eight pounds is really a bare minimum for hunting.
Have fun. E
