Absolute best advice I'm capable of giving......Leave your emotions in the truck.
You're going to look at your first boat, it's going to be shiny and nice and look amazing, and you've spent days thinking about fun times on the lake with the family and lounging in the water with the stereo on, or catching air off the wake, or any other number of things. DO NOT fall in love with your new boat until you sign the papers. Be prepared to walk away if it isn't the right boat, has issues that make the deal less than ideal, or you just don't get a warm fuzzy feeling about how it's been cared for.
Check everything you can think of. Looks at every square inch you can get your eyes on. Open compartments, turn levers and knobs, check under the carpet, check inside the storage areas, look at the trailer, look at the tires/hubs/fenders/lights/coupler. If it "looks" well maintained, it probably is. You can see the true maintenance by look past the obvious things, and looking at the details. Are the pivots well lubricated, or have they just been pressure washed? Is the brake bleed screw rusted shut, or has it been moved recently? All those tiny details are a part of the story of the boats past, you want a good story, not a neglected one.
Good luck. Take lots of pictures so we can live vicariously