RE: British virgin islands
Great fishing down in the VIs. I'm jealous. OK, let's get down to business:
Lots of reef critters -- jacks, grouper, etc. Lots of open water critters -- macks, kings, tunoids, etc. Keep an eye out for diving pelicans and busting bait. Lots of great snook fishing. They cruise the beaches, and you can catch them from the shoreline around St. John, Tortolla, Jost Van Dyke, etc. Good numbers of tarpon if you can find them. They tend to pod up amongst the moored yachts in the coves around the VIs. More hit or miss than reliable fishing, but keep your eyes out for them porpoising. Underfished bonefish flats on the north side of St. John, NE side of Virgin Gorda (Mosquito Island), and of course, Anegada.
Bring a variety of Clousers in different sizes and colors (I suggest #2 to 2/0, lots of chartreuse). These work great on the snook, reef critters, and other ocean goers. Some bigger profile flies -- big Deceivers, for instance. Bring some tarpon flies and some bushy Whistlers. And bring a few Crazy Charlies in case you find some bones up on the flats.
It's a real mixed bag around the VIs, and you just have to be prepared for whatever you encounter. I would suggest trying to pick up some chum (live or frozen) so you can have some fun mooring up around some of the reefs, and teasing some fish up to the top. But the best thing to do is just to keep your eyes open and be ready for different situations.
As for leaders, nothing special needed. Just bring a variety of leader material with you and tie up simple, short leaders. Remember that there are a lot of toothy critters down there, and the snook also tend to cut through leader with their sharp gill plates, so bring some heavy mono and wire for shock tippet.
Have fun. If you need any more info, email me at firstname.lastname@example.org