Since my collection is still pretty small (around 55) I don't really worry about "keeping track" of my coins, as I think I'd notice if one went missing.
I don't retrieve activation codes as soon as I get a coin, I only do that once I'm actually ready to activate them.
I gererally like coins that I revieve in trade to not have had their activation codes already retrieved, but if it's written on the insert I don't really mind.
One odd habit I do have is to keep all the coin inserts I get in a box. Not sure what they could be good for, but I still do it anyway!