After run oil gets put into the engine through the carb and you flip the prop a few times to distribute it. It is supposed to protect the engine from corrosion while it sits. Methanol, the base for glow fuel, absorbs water out of the air and that combined with oxygen can lead to rust. Here in central CA with the hot, dry summers it isn't so much of an issue so most of us rarely use after run oil unless the plane will be sitting for long periods. With the humdiity where you are at in the south though, you might want to use it after every day of flying just to play it safe. I've heard that Marvel brand air tool oil (from the auto parts store) works pretty well for this.

As far as airplane maintenance, I like to give it a good inspection the night before flying and again when I get it home. Make sure all the control horns, clevis, screws, servos, engine bolts, etc. are secure. Ilike to tug on the control surfaces to look for bad hinges and inspect the entire airplane for cracked wood and so forth. Fuel lines are another thing to check. I see a lot of dead sticks due to cracked lines. It all just takes a few minutes and can prevent a crash. I also give the airplane a good looking over after incidents like rough landings.