Congratz on the job, use it well. As said above, new routines will be refined quickly and old ones will get the polishing you didn't know they needed. Many restaurant performers say to have 2 routines planned out for any given night. It also helps to have a 'bonus' or encore effect handy for the especially receptive spectators.
Cards should be fine for starting, but eventually find other tricks that you can do. Copper/Silver Transposition tricks are great, they put something in the hands of the spectator and overall aren't sleight-heavy (they have sleight free versions I believe). Sponge balls are wonderful, think about investing in sponge bunnies too (yeah, they're a crowd favorite).
Rubber band tricks (CMH, Stairway, Jacobs Ladder...etc) can be useful too. Many performers use Ring and String material that has 3 or 4 phases. Each strong enough to be the end of the routine (in case of food).
Just a few things, I'm at work and need to get busy (sounds so bad...)
I would take a look at The Magic Menu, which can be purchased
here. There is also a 6-10, also sold at penguin.
Also take a look at David Stone's book Close-Up:The Real Secrets of Magic. It has a lot of practical advice (and is cheaper than the Magic Menu) and tips for working in restaurants.