It's best to ask permission if you want to photograph someone, especially if you are working in close. Engage them before you pull out your camera. Learn at least how to say "hello" and "May I make a photograph" in the local language—just showing that you've made a little effort helps. Explain to them what you want to do and what it is about them that made you want to make a picture. If approached in an open and friendly manner, most people will be agreeable—many are flattered that someone has shown an interest in them and what they do. In places where there's a lot of tourism, you may run into people who are tired of being photographed—many tourists are not courteous enough to ask permission, and local people can come to feel abused and exploited. The only way to overcome this is to spend time with the people or to go to parts of the place less frequented by tourists.
My still-embryonic idea is to enlist the help of a local acquaintance who would wear a cheongsam (aka qi pao), and take the role of a sing-song girl. The photo shoot would take place in the streets of Yau Ma Tei, and in the parlor itself. Whether the parlor would allow it or not is an open question that will be answered when I'm there. The owners and clients seemed very laid back when I made these photographs.
Get out there. The only way to discover the rhythm of life in a place, and so figure out what to shoot, is to experience it. Many places, particularly hot ones, are active very early in the morning and late in the afternoon but rather in a lull around midday. Get up early, stay out late. If you are on a tour that is scheduled to leave the hotel or ship at 9:00, get up well before dawn. Wander around before meeting up with your companions. If the tour goes back to the hotel or ship for lunch, don't go with them. Rather than take the bus back at the end of an afternoon tour, hang around until after sunset and then take a taxi. Use any spare time to get out and look for photographs. Besides availing yourself of more opportunities, time spent discovering the place will enrich your experience.
Content development complements your photography and helps you grow and earn beyond your photos. If you're a gearhead like photographer Colby Brown, you could write in-depth gear reviews, or publish post-processing tutorials like Elia Locardi, or write a how-to book like Nicole S. Young. If you enjoy travel writing, you could build a popular blog like photographer Chris Stevens, who writes travel guides and reviews popular hostels and adventure tours, complete with photos.
You can offer photography services to any business in the travel/tourism industry at your destination of choice. Opportunities are plentiful, whether you're selling your services or offering a trade. Going skiing in Colorado? Get in touch with local lodges about trading photography for a free stay. Vacationing in Vienna? Talk to the local tourism board about shooting a few photos for a fee. I recently made a deal like this in Cape Town shooting a month-long campaign with their tourism board, which resulted in a promotional blog post and lead to even more work. Remember that a strong portfolio goes a long way, and as it grows, so will your opportunities.
Make use of people to give your images life and scale. If the facade of a particular building appeals to you, the picture may be that much better if you show people walking in front of it. They will give it scale and also let viewers know what sorts of people live there, how they dress, and the like. An outdoor café may be more interesting crowded with people than empty.