Lots of good info already posted..don't think I could add much more.
I've caught at least 30+ bonito this season by boat already. I have not tried from the shore (yet) and only know of a few days when they were in tight enough for shore guys to get them. (my shore fishin in August slows and my boat fishing increases)
They had a two day blitz at menemsha in rage of the jetty jockies but they have not been there in some time now. They seem to be hanging out on the shoals in the sound and just offshore. When they do come in close the key is (IMO) to fish ***early*** in the morning. My favorites are east beach (permit) wasque (no permit and you can walk), and eastville beach for bones. Sometimes they also show up off of tashmoo on the outgoing tide too. But If I had to pick one place.....east beach on chappy. (I don't care for the jetty crowd at menemsha even if there are fish) Plenty of room and they run up and down the beach. Once the albies get there it will be more difficult to land the bones.
Think early morning with small metals and light line and you will connect.
I find they are more finicky as the day wears on this time of year.
Good luck out there!