Perhaps it's because I'm stuck in Minnesota, where dreams of all things Tropico are the only thing that can get me through the winter, but I always tend to build up a tourism industry. (Perhaps I'm taking this game to seriously. I'll never actually get to my island, will I?)
Anyway, bhar is right, the true beauty of Tourism is the consitency of the income. However, nowhere is the old adage more true: it takes pesos to make pesos. Here are a few thoughts on how I make it work. Keep in mind I never open cheap hotels or souvenir shops. They'll just bring down your rating in the long run.
Always make sure you have the overview eye open when getting ready to build. Place your hotels in the green areas. Different areas of the island will be green for high income vs. middle income travelers. As you build up an area of entertainment (pools, spas, nightclubs, etc.) these areas will change colors. Once you have some entertainment in place, an area that used to be yellow for luxury hotels can turn to green. The manual says you should have 5 tourist sites near a luxury hotel in order to increase its rating, however, I think that's based on distance, you don't have to have 5 for every hotel. As a result, you can follow Mexico's example on the Yucatan and devote an entire shoreline to hotels and such.
It's been said elsewhere, but I don't think it can be said enough, beach sites are embarrassingly profitable. If that uneducated fellow working there had any idea, he'd want a piece of the action. Scenic overlooks also tend to do quite well. Even though they cost more, pools are constructed very quickly and make a ton of money. Set these to upscale dress code and the tourism rating surges.
If you are truly trying to build a tourist mecca, then you have to have the infrastructure to support it. Energy, fully upgraded first class airport (there's nothing quite like having a plane land with 17 tourists on board..Cha-ching) and a range of entertainment options. Like SlickWilly said, it's a good idea to have a police station nearby to keep everyone feeling safe. Unfortunately, I've never been able to fill up more than one off shore bank, but there are tourists who have that high on their list of sites to see. Issue the Mardi Gras edict, put out the Tropico commercials on tv, bring in Elvis, and watch the $$$ flow.
I could keep going, cause I just love to make "tourism bloom like a flower," but I'll end with this note. I often have trouble keeping the hotels full of workers. Even one empty spot can cost you hundreds. The more skill your workers have the higher the tourism rating, so the higher the demand. Hotel, pool, beach site, and scenic overlook workers tend to be my highest paid uneducated workers. Make sure they have housing and facilities close enough to work that they aren't wandering around the island all the time.
Good luck with your island. Make it a place we'd all like to visit