When doing a total teardown, I usually put the small parts together in ziplock bags and label them with a felt pen. On large parts I might not recognize later, I put a piece of masking tape on them with the name of the part. If I run into something unusual, I make a written note of it. Sometimes parts don't go together the way they look like they should. Pictures and drawings can also help. Writing down the order of disassembly can also be helpful. There is nothing worse than getting almost everything back together, then realize you have to tear it all apart again because you forgot a part.