First and foremost, think about what made you decide, out of all the places in the world, to choose this particular destination. Whatever it is—the beach, the rides, the mountain, the galleries, the food—obviously appeals to you. If it didn't, you wouldn't be going there. That site or activity (or inactivity) is one of the things you want to photograph. But there are probably many other interesting aspects of the place you may not be aware of. That's where research comes in.
Besides the travel publications like National Geographic Traveler, Conde Nast Traveler, etc., the demand for this genre exists in industries like Travel, Photo Education, etc. Many travel photographers are today leading photo-tours through companies such as Intrepid Exposures, utilising their knowledge of unique travel locations, experience of working as professional photographers and using this to help travel enthusiasts take great travel images during their trips. Many others are doubling up as educators in the field of ambient light photography. Some of them are doing assignments which intrinsically use their strengths, e.g. shooting exteriors or interiors of buildings for architects and interior designers. Photographers like Steve McCurry are often commissioned to shoot commercial advertising work using their skills from travel and documentary photography to produce powerful advertising images.
Some libraries already have enough travel shots, but the big online stock libraries are always looking for fresh images, and want to offer as much as variety as possible. So, if you want to submit to a particular library, check you have a good range of high-quality images that are different from the library’s current selection (and as good as, or better!). Libraries will also take a cut of the money you make from selling your images, typically 50%.
Understanding the customs and traditions of a place is vital. For one thing, you want to be sure you act in a way that is not rude or offensive while you are there, and it's hard to know what's acceptable and what isn't with some knowledge. It can also help you understand things people do that at first encounter you might consider incomprehensible or even horrifying.
Yes, I know that’s a fairly meager living. Especially when spending $2,000 of it a month. But, how many people can say that they get to travel every day of their lives? Sure, I’d love to be making more, but I have no complaints. On a daily basis, I get to see places and do things that people spend their lives saving to enjoy. I wouldn’t trade my career for anything at this point.
Before I get into the “how”, let me tell you about the “how much”. In traveling the world, I spend an average of $2,000 a month. That includes accommodation, transportation, food, etc. I don’t have a home, so that $2,000 is in fact the entire extent of my expenses. Thus, to keep myself from non-under-bridge housing, I need to make that much each month… but preferably a bit more. And, before you ask: no, I don’t have savings, I don’t have a trust fund, and no I don’t have a sugar mama (although I want one).
I have found Alessandro Bergamini's China gallery to hit all the right notes in that regard. Most of his images were made in Guizhou; a province located in the southwestern part of the country, and well known for its traditional rural villages, inhabited by minority groups like the Miao and Dong. Other images in the gallery were made in Guangxi , another autonomous region bordering Vietnam, and home to the famous cormorant fishermen of Guilin. I haven't been but I read that even though the water is too polluted now for fishing to be sustainable, these fishermen are catnip for many photographers, and earn their living in that fashion.