I take notes when in the fields and enter the results in a spreadsheet when I get home. Every week I give myself a 'hitlist' such of things to do or watch out for with the particular hive, such as swarm risk, or predicting when the hive will need another Super, and making sure I have one ready for the visit... just in case. Also record items such as their configuration (eke, feeders, number of supers, amount of food they consume, how much honey I have taken etc).
Last year, being planned and organised made last year run so much smoother.... Particularly when I was juggling swarm boxes of bees or moving them into hives every other week.
Knowing what hive requires what helps a great deal as I have multiple apiary sites and want to move as little kit as possible..
I also like the idea of keeping the components of the hive dedicated to each hive where possible... i.e. if a super has been on one hive, it will go back to the same hive the following year...
Also, some of my hives migrate...
My wife is a forecast planner by trade and she has taught me a great deal over the years!