You have just bought your dream boat and want to start using it, great, start using it and begin making mental or written notes on issues that need to be addressed. If you got service records & receipts for work done your doing great. Most don't so assume it needs the following:
1) Legal requirements, check horn, lights, fire ext. paperwork, (tickets are expensive)
2) Engine: change oil, filter, trans oil, fuel filter, pump impeller
3) Drive: Check prop for bent blades, check strut bearing wear, do a PROPER shaft alignment (annual task)
4) Trailer: inspect tires, lift wheels & spin wheels listening for bearing noise, or simply service the bearings, service brakes, adj.
Boats that are regularly maintained this list can be accomplished pretty quick, for boats that have been neglected this checklist can take several hours, or days. The goal is to have a dependable ski boat!