Got a couple for you!
Been there done that. Don't buy any souvenirs, t shirts, hats, etc. at any of the ports that you visit. Almost all of the traffic they get there are cruisers and the prices are high (er). If you are charting out of Tortola, when you get back, go to Road Town and do your shopping. They have a tourist trap area there and have the same stuff that the smaller islands had at a much cheaper price. Be careful about what mooring balls you use. Some of them are privately owned and cost more to use. The Bight where the William Thornton is is one of those areas. Take lots of money and don't use your credit card if you can help it. My wife used hers once before I caught her and we later got some strange charges from Korea. I've heard this complaint from others too.Have fun!