Fishing journals, many years ago I used to live by these and put the time into them for documenting key information. Then it seemed to be more work than felt it was worth so they went by the wayside.
When you move to a different part of the country, these become invaluable once again and documenting key locations can be valuable either days or even years later. Typically, not going to document each area that fish were caught but picking a key location.
Picking the most productive spot, either numbers or quality of fish, should be the factor when doing this. This is when detail becomes your best friend at a later date and by only picking this one location, you put more effort into writing everything down.
Weather is vital especially in the spring and fall, baits during that weather can put you on the fish faster at a later date. Anything different about the area that you are fishing allows you to hone into that exact spot later. Any key details that you can think of is worth jotting down.
Have fun with it as well as when you read these at a later date, everything will come back so much quicker and your day of catching may be more enjoyable.