I keep a very detailed log each season. I carry a very small, shirt-pocket sized spiral notepad that I use to jot down notes on sets, locations, lures/baits used, model/size of trap, set type, and catches. I spend a little time prior to opener and draft up about two weeks worth of blank log sheets in this little notebook, based roughly on my scouting of where I am anticipating some sets (mostly land-based, canine or cat sets). 1-page per set, with a log based on my note-taking style and data needs. Then all I have to do is "fill in the blanks" as I punch in sets and check them daily. After season is over, the furs are put up, equipment put away, etc. I go back and transfer my little notebook information over into my computer into a database I built for tracking the info. I use Microsoft Access, and by coding my data accordingly it is fairly easy to query 10 years worth of set data. Kind of interesting to see performance of certain sets, environmental conditions, trap size & model performance, lures & baits, etc.
It's a lot of work to keep the data current, especially if I am running late on time or energy, but its something I've committed myself to also. I feel if I keep my own set history that I will have something very valueable for both myself and my kids someday.
Jim-NE