, first and foremost, at least the gear
required to pass the Coast Guard safety inspection
A handheld GPS if you can afford it. As a backup.
A small medical
kit for any possible injuries.
is nice but not essential, I sailed for 25 years on the NE coast without it, but it sure is nice in the fog
Beyond that it's getting into creature comforts.
I do agree with the earlier posts to take a safety course and a navigation course, I took one way back, then again 10 years ago to refresh my memory and purge bad habits, I would do it again but am looking to get my captains license
and the courses required for it include navigation. The courses help put you in the right frame of mind, the information is invaluable.