Normally there will be a desk managing a "waiting list" when you first get to the poker area, even if there are open seats. On a Friday night, there will be a waiting list or at least a que to get seated. You don't just sit at an empty seat in most cases.
You will either get taken to a seat right away or put on a list. If on a list they will have a way to contact you, you shouldn't have to stand and wait. If you do have to wait, find the house rules hanging on the wall in many rooms and read it.
You will get chips once you are assigned to a table, maybe via the desk, maybe via a chip runner, maybe from the dealer at the table.
The dealer manages the game and the chips. Place your wagers in front of you and the dealer will do the rest. Never ever make your own change. Don't splash the pot. Remember the single chip rule. Always better to say what you are doing than just doing it and hoping everyone understands your intentions.
Watch what is going on for a bit. look for things like a betting line or a forward motion rule. The goal is to get a feel for how thing work more than getting table reads. Table and villain reads are good but as a "new to casino poker" kind of guy the first order of business is getting comfortable.
Buying in short till you get your "sea legs" is a good strategy. More so if on a limited budget.
The players come and go quickly. It is hard to get good reads fast enough.
Don't worry about tells, "mixing up your game" or anything like Game Theory Optimal poker. The villains are not very observant and you are not playing that many hands.
ABC TAG is fine. People bluff less than you think. You can get along just fine with a pretty passive game. Perhaps not optimal, but not generally a disaster. Being a calling station is a disaster. So, tight passive (TAP) is ok, loose passive (calling station) isn't. Folding preflop is good plan.
Keep in mind the goal is to have a good time. It is fine to lose $300. You are in a casino, you are intended to lose your money. It isn't as though the black jack or craps tables are any better than a poker table.
Good luck! -=- DrStrange
PS take any racks of dollar chips you have after playing back home rather than cashing them in. Harvesting baby!