One thing I would recommend is taking a night course on boating, my dad taught one for years at Assabet Valley for the Coast Guard Auxillary. Cost is low and it can be very helpful. It is amazing some of the stories he told me about guys with zero water experience and the large toys they had to own to keep up.
I took a 2 day coarse along these lines. i took it back when my father had a 28ft ocean boat. It was interesting to hear some of the stories.
I think the merrimac river actualy has the most accidents by far. I have owned my own boat since i was 13 and lived on a lake for most of my childhood.it was water skiing back then but alot of principles apply just the same.
My wife and i also took the mandatory boaters safety coaurse for N.H. She was pissed when she found out it was an 8 hr deal.haha
But honestly i think it should be mandatory for all boaters to be licensed in all states. Even if you don't plan on buying a larger boat and motor i think the 1 day coarse would be informative. I do think a day on the water with someone would help if you have any questions. There are a couple tricks with backing up and docking that would be good to learn 1st hand.
It's not that bad at all but it is also better to be safe and know the laws.