I just "summarized" my boat last night... Anyway its different every year but basically do all your maintenance for the coming season either when you winterize or summarize. No one wants to do it when its nice!
This year I steam cleaned all the carpets, 303'ed everything, cleaned everything inside and outside the boat!
Installed new spark plugs (the old ones had 300hours on them) cleaned all spark plug wires, closed all petcocks, tighted all hoses, new alternator belt, new impeller, changed oil and filters, charged the batts and topped off the gas tank! Wualla ready to go tonight or tomorrow!