This is just how I roll, buut I would never take a "new to me" boat out until I have done:
A full tune up to include cap rotor points condensor wires plugs timing adjust carb adjust.
Check all cables for smooth operation, connection, corrosion. Shift adjustment.
Oil change new filter. Fuel/water separator filter. Check fuel hoses and tank for crud.
Cooling system hoses and hose clamps. New water pump impeller, check circulating pump for wobbly bearing and weep hole. new belts.
Change oil in drive. Top up trim pump. Check trim for operation.
Check electrical connections for tightness and corrosion. Dielectric grease in main harness connector. check all fuses.
Turn steering lock to lock. Top up power steering fluid.
Make sure bilge pump operating properly.
Ditto bilge blower.
Lights and horn working.
New batteries.
Engine mounts and stringers for corrosion. Clean and grease.
If all that passes, the boat should be good to go. Always tell someone on shore when you are going out and when you expect to be back. If you know tell them where you expect to be.
Wear you PFD if you are the only one on the boat. OK wear it anyway even if you aren't. If you can't stand the bulk, get the auto-inflating Mustang one. Yes it costs but I would guess that given a choice between spending 275 or treading water until you drown that you'd spend the 275. Also, if you are going out solo, get the autotether thing that kills the engine if you fall overboard.