My biggest tip would be never stop looking. Be resourceful. Check threads, check Photobucket, different forum sites, whatever you can.
Another tip would be trade me the Postmarks signature and the Same Day signatures autos. I'd be willing to look through and see what I have of other duplicates (those are two that I collect multiples of). If you'd entertain offers for those two, let me know. I bet I can put together a few autos, #ed, etc.