I’ve been a group ex instructor (in mumbai, India) since the last 16 years teaching a cross training class (aerobics, step, tabata, bootcamp, etc). While my classes bring in an average number of people, i would like to reach out to more since i have so much to offer in terms of knowledge and experience.
In addition to the suggestions Lori and Ariadne mentioned, you could try to advertise to the communities and neighborhoods where personnel from the different embassies and consulates reside. Another option would be to partnered up with some of the resorts that might be close to you and offer classes at their locations. Mumbai can be a very popular destination for people from around the world and these resorts are always looking for experienced instructors like yourself.