Find places with long, soul-crushing queues and crowded waiting rooms and build entertainment snack bars next to them so that people can have fun while waiting to be called.
Make people's day a little bit better. (good for them)
A simple business opportunity for the person that solves an annoying problem for others. Customers guaranteed. (good for you)
Make people that are waiting for someone else's service less unhappy. (good for the other business/venue)
Specifically, look for places that have crowded waiting rooms or long queues.
If possible, rent, buy or build a place adjacent to the one where people are queuing. Otherwise, look for another suitable place.
Make a deal with the queueing place owner to create a direct entrance between their waiting room and your entertainment establishment.
Establish a calling system where people take a number and see an estimated waiting time.
Extend the calling system to your establishment so that people can always see/hear when their number is up next.
If your place is big enough, try to accommodate different types of people. Some like to chat/socialize, others like peace and quiet. Some people like to play arcade games, others would appreciate a comfortable recliner where they can dive into their phones. Offer snacks, drinks, etc. Come up with ways to make people forget they are queueing.
So you don't solely depend on the waiting room business, have an entrance from the street so that anyone can walk in. People are more likely to come with friends so that they can have fun together while one of them waits for an appointment.