most of the things, like lower unit oil should have been done at the end of the season prior. What I do, recharge and install the batteries, crank the engines and let all that gunk out. After that is finished, I replace the plugs. Some people replace the plugs before the first crank, but why get all that smudge on the new plugs. Touch up bottom paint if using multi season. Power was and wax. Check all electronics, navagation lights, etc. Don't forger to put in the drain plug, launch and fish..