Like someone said before, always trim your motor down when you park it after your trip. This keeps water out of the lower unit and drains it from the water pump. If you forget to do this, the water will freeze, causing the seals in your lower unit to rupture. Hello new lower unit $$$$.

Also, put fuel stabilizer in your fuel before you go out and run it. When you put it in your fuel tank before your trip, the travel (sloshing around) will allow it to mix with the fuel properly. Gasoline these days contains ethanol. When ethanol and gasoline mixture is stored, moisture is created and you now have water in your fuel tank if it is stored over a period of time. If you start your motor, there will then be water in your fuel system (very expensive to fix). Your fuel is fine after you put the stabilizer in. Use CRC Fuel Stabilizer or Sta-Bil Marine Fuel Stabilizer. Also, if you run the motor with the fuel stabilizer in it, it will essentially "fog" the injectors and keep them clean from any corrosion.

If your motor is a two-stroke, look into some fogging oil if you plan on storing the boat for a while.

Just remember to raise your motor back up before you plan on hooking it to the trailer and taking it on another trip!