Re: first boat, need advice !!
first of all, remove any old fuel from the tank and start with fresh. Next, take it to a mechanic to have the carburators cleaned and overhauled if necessary. Have the mechanic check for any old rubber hoses and other seals that need replacing. Heck, just have the mechanic go thru the whole engine for preventive maintenance while you're at it and possibly change the lower unit oil and check it for pressure to test those seals as well. Also replace the water pump.
Why do I recommend all this? My first boat sat up for years before I purchased it. The gas tank was full of crud. I had a faulty water pump that caused the motor to overheat and $800 to repair. Later I had the rubber over-pressure relief or some kind of do-hiky pop and rain water all over the engine. Next, the primer bulb quit working. I babied the wiring with liquid rubber as the insulation crumbled off. After working all the kinks out, I enjoyed fishing, but initially it was a gamble at the ramp for a few trips.