Multiple clients works good.
Small workshops for 2-3 hours on weekends can show kids the proper form of lifting. Great because teen education in the gym is overlooked alot these days.
Offering advanced training plans for motivated people. Some clients of mine have the willpower to come in and do their workout, but dont know how to set one up for themselves. I’ll meet them once a week/month and get them on a plan.
Open up a studio and begin to grow. Hire another personal trainer. Rent your space out to the many fitness organizations that are listed on this site that offer workshops and offer a workshop at your studio. Likely you will get a complimentary workshop, exposure and you get to see and hear the many fitness professionals who will attend the workshop who might likely become your employees.