Fish notes can give you a big advantage over the everyday angler that does not keep them. When I first started keeping notes on my fishing adventures, it didn't seem all that important but now 6 years later I use them for every fishing trip I go on.
After the first few months of keeping notes, you will be able to start to see a pattern. After a year or two of keeping good, detailed, notes you will be able to go to your best fishing spots that are producing fish by looking back on the previous years worth of notes.
When going back through your notes, you will notice that fish feed on different types of food throughout the year, so this will help you have an idea on what bait to use on your next fishing trip.
Another thing to do when keeping notes is to label your fishing pictures with the date, where you caught the fish and the bait used.
Here is a link to a printable
Note Template page of what I use for keeping my notes. Feel free to print it out and start your personal journal. If you do this after each fishing trip, you will consistently catch more fish.