Inspect all hoses and hose clamps (water and fuel).
Once at the water run it on the trailer for a couple minutes and inspect for leaks before taking off and having to make a beach landing to keep it from sinking. 
Who are you referring to Keith?
Welcome! And X2 on everything he said........and tighten all yer hose clamps.......don't ask how I know that.......twice.......
Sounds like you already did, but check your trailer tires, springs, hitch, that sort of stuff. 'Bout to get to 115+ degrees out on the freeways here in the Desert, and I'd keep a spare in the truck if the trailer doesn't carry one, as well as about a 10" piece of 4x4 (PM me and I'll tell you how to use it to jack the trailer up if its a tandem....)
I would also recommend putting together maybe a shoebox or bigger sized plastic container with basic tools in it, (Vise Grips, Adjustable wrench, basic hand wrench set and screwdrivers) plus a spare coil, ballast resister, some wire, connectors and fuses (If your boat is equipped with any of that stuff), tow rope and jumper cables.
Worse come to worse, you never get into the box, boat runs flawlessly, you have fun, and the 'ole Lady doesn't rub it in what an idiot you were to buy a boat..........c'mon, I'm not the only one that heard this.........
C-ya on the water
Ray
