A. Smart thing to do with a marked-up ms from your agent/editor:
1. stack pages neatly
2. punch holes
3. place in heavy-duty 3-ringed binder
This makes it very convient to lug around. You don't lose pages, you can mark them easily, and fold back certain ones to make your place or help you remember a section you need to work on. I did this the first time. It worked wonderfully!
B. Stupid thing to do with a marked-up ms from your agent or editor:
1. schlep all 400+ pages around in the original mailing envelope because for some reason you're too lazy this time to do number A.
2. get them mixed up, of course
3. be sure to let the whole shebang fall out of the envelope outside in the pouring rain, your agent's felt-tip-pen scribble notes dissolve into a green blur, and you're stuck with 400+ soggy-out-of-order-totally-unreadable-pages. Oh, and bump your head in your frantic scramble under the car to retrieve the pages.