Here's a tip that confounded me for weeks, and still trips me up sometimes when I'm overloaded with bags...
You're carrying 3 large bags. You want to condense that down to one. The bags have the same sdesc, because other than their contents, they're identical. Problem is, every time you do something with one of the bags, it keeps moving up to the top of the "inventory" list. So here's what I do:
l in bag
this bag has just some feathers in it.
l in 2.bag
this bag has just some shards of agate in it.
l in 3.bag
this bag has feathers and shards of agate in it.
get feather bag
get feather bag
(repeat til your hands are full)
put feather 3.bag
put feather bag
put feather bag (til your hands are empty)
get shard 3.bag
get shard bag
get shard bag
put shard 2.bag
put shard bag
etc. etc.
Things move in numerical order, so when "bag of feathers" was 1 on the list, and you put your hands into 2.bag to get a feather, the "bag of feathers" became 2.bag and the bag of feathers and shards became 1.bag. Then, when you put your hand in 3.bag, which hadn't moved at all and had the shards of agate in it, THAT bag became 1.bag. And the bag of feathers and shards dropped down to #2, and the bag of just feathers became bag #3.
Very frustrating when you mix them up, but remembering how they get ordered, and remembering that every time you put something in or take something out, it shifts the list, is helpful.