The biggest mistake I did is not to read the owners manual, I would have saved thousands of dollars, and some headaches.
1. Dont ever charge your boat battery with running car/truck.
2. Make sure to always check inside the engine bay after you start your boat (make sure no water is coming in)
3. Make sure you have a brand new battery, or completely charged battery a lot of problems in my experience is a bad battery.
4. In my own experience I always have a life vest, I almost died 3 weeks ago, AND I HAD A VEST! I would definitely not be here if I didnt have a vest.
There is my two cents, good luck and be safe!