What kind of motor? I/O? Outboard? 2-stroke? 4-stroke? How long has it been sitting? I'd make sure to check gear lube, that its pumping water like it should, and of course that it has sufficient and clean oil (depending on what the motor is). Depending how long it's been sitting...might want new plugs too. It really all depends on the motor and how long its been idle.
If you've not changed (or know when it was changed) the impeller, I'd look at doing that and then confirming the system is cooling like it should. Make sure you've got a good charge on your batteries and things are shifting like they should.
I usually treat my first run out in the spring like a "shake down" run ... second time out is usually for family fun