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.
The best marketing you can do is probably grass-roots marketing where by you reach out to the local community by placing business cards in the area and with selected partners like hairdressers, beauty salons etc. Try to stike a deal with these establishments like a special offer for their customers or 20% off. I also used to run a free fitness class in my local church hall. I didn’t charge but the amount of work I got from clients off the back of this was really good.