Advice? Getting in to Boating/Fishing

[wbnh]

I'm a Portsmouth, NH shore fisherman who knows no one with boats or technicians at a marina.

I was exploring some of the many options on Craigslist and others for purchase of a used 18-22 Center console for river fishing and maybe a bit of the coast.

Other than "don't do it", what advice do frequent boaters have for getting in to boating?

I haven't yet completed the state boater safety course, which is one prerequisite, but what other instruction is available? Who can teach boating and fishing the seacoast?

What are the options for keeping a boat in the water for the season? I understand that slips and moorings can have wait lists and are hard to get. Are there ever unused ones available mid-season?

Of course money is an issue, so the cheepest options are always appreciated...and I know trailering is cheepest, however I still would like to keep a boat handy in the water, even if it costs a couple of grand to rent a slip.

Thanks for any and all advice/instruction.