* Belize has serious bugs. We took a repellent with 28.5% DEET, and it didn't even slow the sand flies. Next time we'd take Jungle Juice (REI carries it), which damages plastic sunglasses and watch crystals and can't be constantly worn, but is 95% DEET.
* There are some serious, dangerous snakes, though you won't likely encounter one. The fer-de-lance or, locally, yellow jaw (for the yellow streak under its head) can be long, very poisonous and fast. But the "jumping tommygoff," a short, thick viper is my favorite. Many Belizeans call any snake a tommygoff, but the real thing, most believe, can jump 2 feet, and backward, when it strikes. Snake experts say that's exaggerated. Yet they agree that it's so powerful and fast that it can twist and strike in a way that looks like it's jumping. The basic precaution: As in U.S. rattlesnake country, don't put hand, head or foot anywhere that you can't see. Many snake bites, for instance, occur when people step over a log without looking at the other side first, or stick their hand under a porch step--startling a snake.
* Guides: Hire only legal, licensed guides since they're most likely to give you accurate information about the plants, animals and history. They're expensive, but I'd at least hire a guide for the first day or two, just to get oriented. When making the deal, be clear whether you're quoting U.S. or Belizean dollars (BZ), which are worth half the U.S. dollar, and whether the 15% value-added tax (VAT) and gratuity are included.
* In the jungle, stay on the path. Even locals do.