Personally, I would first recomend some books and DVD's.
There are a couple books on Restauraunt Magic listed in the reviews above. I HIGHLY recomend On the Spot becuause that really is a walk around restauraunt routine. I have had people come up to me and say "show me a trick" and so I will pull out a deck of cards and they will hand me something like a quarter or pen and say "do a trick with this." I would also recomend Card Magic. If you are'nt to familiar then I would say get Born to Perform, otherwise something more experienced, maybe one of the Gregory Wilson DVD's. One thing I really enjoy is instead of using a standard deck, I bought the Boris Wild Marked Deck, and used that for both impromtu routines and mental routines.
Some other tricks you may find usefull are
1) Pen Through Dollar
2) A TT (look at Darwins vided for ideas)
3) the Raven (I would advise the bonus package)
4) Card toon(neat little effect)
5)Holy Moly(some what tricky, however with lots of practice can pose a very neat effect)
6)Just Name it(can be purchased at www.elmwoodmagic.com
7)Hip Hop Pocket Mullica
Three Card Monte depending what restauraunt your at.
9)If at a nice restauraunt, the Time Machine will probably do well
(PS. I dont know if you know however the Self Levitation on Mind Freak once finished with the gimick costs around 250.....so I would be careful before you waste your money on what kind of effect your looking for.)
Any Questions dont hesitate to ask!