Draft the floor plan of the hall to scale. Use graph paper with a scale of four grid squares to a square foot. Designate permanent features such as doors and food service stations. Decide where to place the stage if that is an option. This is a critical decision, because stage placement determines sight lines for the audience, as well as placement of lighting equipment and stage scenery. Cabarets set up for theater-in-the-round are limited in terms of the sets that can be used. In-the-round cabarets must be lit carefully so the actors are visible from all directions but the lights don't shine into audience members' eyes. Designate "escape" aisles for actors to enter and exit the stage, and plan on leaving these aisles clear.
Take measurements of your available stock of tables and chairs. Long banquet tables are the least attractive and useful tables for cabaret theater. Most of your audience will be made up of couples who won't enjoy being seated cheek by jowl with strangers. If possible, provide square or round two-tops, four-tops and larger banquet tables for six to 10 people. Round is always preferable to square tables. Audience members will need at least 24 inches of space in front of them in order to dine comfortably, a little less if they are only eating dessert or drinking beverages.
With the correct number of chairs in place and pulled well away from the table, measure each table size. This is the overall "footprint" of your table and chair setups. Guests will need extra space to get in and out of the chair.
Cut heavy paper into scale-model representations of all your available table and chair footprints and number them. Place them on the scale drawing of the floor plan and arrange them until you can fit as many of these footprint models as possible into the open floor space. Leave a little room around each footprint model to account for aisles between tables. For true comfort in seating design, every seated person must be able to see the stage but can still place at least one elbow on the table.
Try the plan out. Arrange the actual tables and chairs according to your design. Sit in every seat and look at the stage. Will this audience member have a good view? Will other heads be in the way? Make adjustments as necessary. Remove tables or reduce them to smaller two-tops if necessary. Never knowingly cram people into seating that gives a poor view of the stage or makes dining impossible.