I always find something new to learn each season.
For instance this fall I tried some UV paint on my water decoys. The paint went on fine and didn't look too bad either. I put it on following the manufacturers directions. I also let the paint cure on the decoys for 3-weeks before using them. The problem was, that after several outings, the paint started to come off. I should have sprayed the decoys with a clear finish top coat before I used them. That probably would have kept the paint on them.
Another was to always keep some spare parts in the boat for your outboard motor. Late this fall, I had a plastic fuel line fitting partially break where it connects to the tank and the "O" ring was almost out of it. I was lucky enough to put the "O" ring back in the fitting and continue my hunt. A spare fitting was only $7.00 and will now be kept in the tool box.
So, school is out. What did you learn?