If you've not operated an I/O powered boat there are some things that you absolutely need to know. If this is a trailer boat, before you leave your yard or storage area, inspect the exterior of boat, especially the outdrive. It should be obvious what to look for but a puddle of oil beneath the drive would be a sign of an issue. Raise the engine cover and check oil, power steering, belts, hoses, plug wires etc. Fix things now so you don't need to call for a tow off the water. Check trailer tire pressure and that the boat is secured on the trailer. That includes bow and stern tie downs. At the ramp, before you turn the key: 1) Know what the blowers are for. If you don't know, they ventilate the engine bay ridding it of gas fumes that can go "kaboom".. 2) Know when to operate them, Operate them for several minutes before you turn the key. 3) Ensure the blowers actually work. I've just touched a few major topics. You will need to experiment with "trim" but your behind is the best gauge for the proper setting. Trim up a little to get on plane. When on plane begin tweaking the trim up and down to find the best setting. Trim is about right when you hear the rush of water at the side of the boat become much quieter. The boat will also tend to flatten out and ride smoothly. Always trim up when approaching shore to avoid hitting the bottom. As was pointed out, trim up too far you being binding the U-joints and breaking things. As with any vehicle, use common sense.
(at least on the trailer, it is actually illegal to go down the road with the plug in the boat in many states)
