Decide whether you want an internal or external-frame pack. External-frame packs are cheaper, ventilate your back better and allow easier access to pack contents. Internal-frame packs are better padded, have greater carrying capacity and allow you to place more weight on your hips.
Step3
If you intend to use the backpack for casual day hikes, get a small, internal-frame model. For overnight trips, opt for a medium-size internal or external-frame pack.
Step4
You will need a large internal-frame pack for extended trips. It will keep the load closer to your back which is easier to carry.
Step5
Once you decide on your pack, go to an outdoor store and try different models and types.
Step6
Put weight in the packs to simulate what you will carry in the wilderness.
Step7
Many companies make packs for different body types. Try on various sizes of the same model.
Step8
Beware of too many features such as excess straps, pockets and adjustment points, which add weight to the pack without adding function.
Tips & Warnings
Simple is often better.
Packs that divide the main compartment limit your ability to really stuff the pack full, but make it easier to access items loaded at the bottom.
Don't be oversold by sales people. Their job is to hype features. Buy what you really need, nothing more, nothing less.
Make sure the pack's top flap stays over the main compartment when the pack is fully loaded.