Provide a complete backline. The backline is a set of equipment musicians and performers expect to find at a sound stage. This includes a bass amplifier, at least two guitar amplifiers, a keyboard amplifier, a public address system, microphones and a complete drum set. Your sound stage should include all of these items. You do not have to provide guitars, keyboards or any other instruments, because musicians will bring their own. The drummer may bring his own cymbals, snare drum and kick pedal to attach to the drums.
Soundproof your rooms. The quickest way to lose clients is to allow their rehearsal sessions to be interrupted by sound leaking from the next studio. You also must prevent sound from escaping from the room your clients are in and disturbing neighbors. Use soundproof foam, corkboard or acoustic panels to hold the sound in.
Provide on-premises management. Do not rent out the room and walk away. Maintain an office where clients can come with problems. Keep your billing computer there in case clients have questions about charges. You can also help them solve problems that arise, and lock and unlock the front door late at night.
Avoid over-billing. Don't bill for every single minute a band or performer goes over the time limit. Reasonable time to load out instruments should be allowed. Musicians do not respond favorably to having the clock watched when they are being charged.