Just some random stuff, kind of more Yamaha related.
Before you go: Go ahead and put the drain plug (and clean out plugs, otherwise leave them out) in before you leave for the water, might as well. Buy a multi-meter and check the batteries, normal voltage is 12.6 on fully charged battery. Start battery at 12.0 or under? that is not OK. Even if you follow directions and start the blower before starting the engine, go ahead and open the engine compartment and let that air out some. Start up the engines for a few seconds just to make sure things are right and the lanyard is set. Check the hose clamps every few trips.
Trailer: If you have bias ply tires on your trailer - if not immediately, you WILL eventually upgrade to radials. After a couple of times of being on the side of a busy road putting the spare on, never mind just the hassle, you will say screw this. Its a safety issue IMO. Don't totally cheap out on the replacement radials either.
Trailer: If you plan to "just use the tow vehicles lug wrench" make sure its the same size as the lugs on your trailer. Same can be said for the jack.
Trailer: You might need to move the winch back on the trailer 6" to 8" depending on your tow vehicle to reduce the tongue weight a little. Factory placement does not work for all tow vehicles. If it doesn't feel or look right, then its probably not OK.
The boat ramp: If you are new, see
@jEt_jAk 's post above. Take it slow and make small corrections. Overreacting makes things worse. Contrary to popular belief there are boaters out there who understand what you are going through. If you are a trailer backing jedi - give people who are struggling some grace.
Fuel: Don't buy it at the marina unless you keep it there in a slip or mooring, just don't.
Preparedness: Things to keep on the boat - Sharp knife, strong flashlight, a couple extra dock lines (15' is good), a few common tools.
Buy in bulk: Food and drinks tend to cost a fortune when bought in single trip quantities. Save yourself the extra 30% over the course of a season by buying by the case for soda, beer, water, chips and snacks, or whatever at the start of season. We tend to like bringing cold fried chicken but don't buy that for the season
. No one was ever sorry about having extra ice.
After trip: Plan on spending a couple hours and maybe a bit more after trips to clean up the boat, de-trash, remove sand, dirt, etc. Waiting to clean it just makes it harder as these "things" dry and begin to cake on or begin to discolor vinyl and even gelcoat. Get it off early. Let it dry out before covering. Keep any extra ice cold beer in the cooler next to the boat so you can drink it while cleaning, its better that way. (I'm a fresh water boater [currently] so 2 hours or so is what it takes me).