Thread: "Fitting" a pack

How is/should a pack be adjusted to fit you? is there a formula or rule of thumb?
Iv always just put the bastard on and carried it, on a long carry or heavy pack I find myself tightening and loosening straps to alternate weight from my shoulders to my hips and vice versa.
Anyway got myself a elberstock and while it feels comfy havent used it yet and noticed it has a few adjustments so might as well get it right and make it easy on myself.