I swore one could go from the SE USA to St Kitts w/o HF. but I could very well be wrong.
Do you have older equip? first be sure it works if you never used it!
Are you RVSM approved? check your route.
Other than that there is not much to it. Tune the appropriate freq, click it once to get a signal (click the transmitter once) then you will have HF! (tellltale annoying static)
Do you know how to give position reports? the format is surely on the high charts of the route you are going, if not the whole deal is on Atlantic High chart 1/2 (Its a wealth of info) If in doubt if they want a position report or not, I usually start with "N12345, position"...if they want one they usually say "Go Ahead".....if not they may just say "report VC Bird this freq or VHF 123.55" or the likes.....it gets a little confusing down there but it all works out....Atlantic flying is easier (err less frustrating I should say).
Im not a huge fan of the islands. but I like St Kitts. It is realtively clean, friendly people. Get a tour of the end of the island with the wild monkeys, also there is a dormant volcano and lots of old sugar plantations.
If you are working for a generous fellow, go stay over on Nevis. Its a 10 min ride on an islander right from where you will park. There is a Four Seasons there that is one of the nicest in the world.!! (IMHO)
Have Fun