I am to lazy I guess as I have never done it. I should have started it 30 years ago. Anyway you want everything in it. What month/day, weather with temps and all other parts like cloudy, Barometer readings with falling or steady to rising, etc, etc. You want where you fished and what you used with time, depth, type of cover your fishing. Just every bit of info you can come up with. Over time it will let you have very good info so you can follow your past success and add new ones.
I bet if you do a search on Google it will give you lots of good info on that.
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