Fewer and fewer casinos offer poker because of the relatively slim profit margin on the game. Whereas slot machines provide a substantial house percentage, poker tables require dealers, waitresses, cigarette girls, and a manager to keep everything running smoothly. The house supports this with a "rake" (a percentage taken from every pot). This can range from 5%-10%; usually with higher rake games, a limit is placed on how much the house can rake (10% with a limit of $5).
Some casinos require their players to check in and out of their tables. This is to keep a record of how many players they have and to manage limited table space. During peak periods (Friday night) there may be a waiting list for poker seats. In this case it is advised to get on multiple lists (be waiting for both 7-stud, and hold'em) and not go too far.
As far as chips go, this differs from place to place. Some will have you buy-in at the table, while others require you to have them already exchanged from the cashier. The best policy is to ask if you are uncertain.
Once at your table you may realize that not everyone antes every hand, thus making it possible to fold early for "free". The betting system used by most casinos is what is commonly called "blind tiger". In hold'em, the player to the left of the imaginary dealer (signified by a button) places a small blind bet regardless of his hand the player to the left of the small blind places a big blind or blind raise. In Stud, the low exposed card usually has a forced initial bet. In this way everyone eventually antes a much smaller amount (about 40% of a betting unit) for one hand.