personal training...
I work out of 1 very small gym and my home as well. I train people as an interest, not as a sole money maker, so our goals are probably different. I also teach circuit training classes.
So I use client testimonials and post that on the website from time to time and dispaly them throughtout the gym in proper areas. Clients of mine are also great about telling others of their success and how much more focused they are when in my class or in one-on-one training. One girl has lost 60 pounds in 6 months, and everyone sees her success, and then asks what she's doing.
I also have access to all member's files, so I target those members that have professional jobs, i.e. "make great money". I simply ask them if they are satisfied with what they are doing and then explain how I could help them further their success. Also, being that I'm in a small community, everyone knows everyone's business, so I usually know who has a big wedding coming up or a class reunion, or the like. I'm sure you know taht there are many out there who simply exercise based on events coming up in their futures. I simply approach them and ask them if they what to make sure to reach their goals by that target date. I don't do flyers, no ads in papers.
I also target teens that want to prepare for sports, and I develope sport specific classes and personal training, depending on their age and ability. This is the easiest by far, as all kids what to add mass, run a faster 40 time, get a D1 scholarship, etc. If you can get just one kid, the others will want it as well. Just like when a kid gets an Xbox360, Hollister sweatshirt, or whatever, they all want it.