I have been running a pirate campaign for quite awhile and some that I would add are:
Be careful how evil you let the players get. Too much evil is difficult to run especially in civilized port cities.
I have allowed my players to learn new tool or skill proficiencies using downtime on the boat, there’s a lot of traveling and this helps give them incentive to use the boat more.
Don’t take away their boat more than once or twice during the campaign for narrative reasons, it gets old and they invest a lot of money and resources into it. If they mess up and lose or sink their boat, that’s on them.
Make sure there’s enough quests that need a boat, otherwise they might revert to old habits of traveling across land.
I have been running a pirate campaign for quite awhile and some that I would add are: