Start a Members Club:
Example:
They pay 30 $ in Members fee for the rest of the year. For this they get
* 15 % discount on either soda or beer
* 25 % discount on table time
* 50 % discount on table time in weekends
* they get invitations for "special nights" only for them
You get their contactinfo (emails).
We did something similar on the hall I ran. It was popular, and ffter a short time we made money on the entryfee, and we got tons of emails so we could advertise tournaments etc.
Emails like:
"25 % discount on this Sat 9-ball tournament for Members"
"One free soda for Members this Thursday"
The offer to them doesn't need to be special or something big. They have already got a good deal with becoming Members. The secret is to remind them once or twice a month that YOU exist, and make them come to your place to play pool.
Another thing we did was to sell cheap cues made in China, with fanzy layouts. The cues sucks, but they are so cheap that people buy them. And they bring them home, and most likely put them next to the door, so they see the cue every day when walking in and out. It reminds them of YOU, and they will play.
Another thing we discussed to do, but never did, was to sell chalks with an advertise for your room on. When customer comes to play, tell them that they can borrow a cue for free, but to play in your hall they will have to bring their own chalk or buy one of you for 0,5 $. (They do this in for example badminton or squash, you rent both the racket, the balls, etc. People won't complain, special not if this is a new room). All your customers will buy the chalk, and since they bought it they will put it in their jacket, and they will often be reminded of your poolhall...
Also you can make posters to put up on the restroom, so your customers can read when nature calls. Not a fancy poster, but a short message about what's up this weekend. Important to change it often.