I have Cobra Jet Steering. It is a big difference, night and day - you will notice it. Boat tracks much straighter and slow speed maneuvering and no wake are much better to handle, at least for me.
I went to Harbor Freight. Bought a a bag and tools just for the boat. Zip ties, wrench set, socket set, vice grips, spark plug socket, extension for 3/8's in drive. Torque wrench, oil filter wrench, pliers, Screwdrivers, curved knife and straight blade knife (for getting stuff out of the impellers), a small plastic storage tray to fit in bag that has spare fuses. Also Allen wrench set. Had to add a larger size as well. I chose a bag that zips across the top since when I put it in storage it doesn't slide around. I put a flashlight in there as well. Electrical tape. Then I bought a plastic container for organization with locking lid. In there I keep grease, two quarts of Yamalube 10w-40, duck tape (can fix anything), Yamaha spray lubricant, a funnel for oil and several spare spark plugs. A few more things I can't think of off the top of my head. I figure I can handle 90% of the things that could come up. In the truck I keep jack stand, Ring Free Additive, Stabil 360, a grease gun and bearing grease in another bag.
I flush after every outing. Although probably not required, but I may suck up sand and silt at the ramp. I pull the impeller plugs after every outing and inspect and leave them out till the next run. I make sure there is a bit of lubricant on them as well. Finally I open all drain plugs and put tongue up on a jack stand to let any residual water leak out.