First trip I would look at the boat I have for sale!emoBigsmile , if not here is some pointers.
#1- the finsh of the boat= has it been left outside or undercover, scratches, gel coat cracks,peeling, you want to look around the transom for cracks.
#2= you need too check the conditions of all electricial hardware, switches, lights,pumps listen to hear if they run,livewell and bilge, fishfinders.
#3-conditon of carpet in the boat, also for soft spots in the floor of the boat.
#4-the motor, you want a compression check on all cylinders, you want all the cylinders to be within 10% of each other, also check foot for water or if possible have them do a pressure check, if oil is leaking around the prop shaft it needs seals, maybe have gear damage.
#5=check condition of trailer, rust, tires, bearings.
#6 almost forgot check steering wheel to motor for loose motion
these are just a few things to look for when buying a used boat.