Just play your game, don't let the fact it's a live game or your first tournament in a casino affect you negatively in how you play. There is no need to fight over every pot in the first few levels. Take it slow at the start, watch the players and see how they play, adjust your game accordingly.
Be aware for casino regulars for many reasons, be aware but not intimidated. If players are chatting with each other at the table from the start they probably play with each other a good bit. Likewise if they seem to know the staff on a first name basis, they'll likely be regulars. Don't be surprised to see some weird hands go to showdown from regs. For example one of the local casinos here the regulars are obsessed with 2,3(calling it the powerhouse). They will literally do anything to get that hand to showdown just to show it to the other regs. If you see something like that make note of it, you might find it useful.
You will find a lot of the live only players will be playing a very different game in comparison to what online is like, especially older guys. For example you'll probably find a standard open or raise is bigger than you'd see online. Obviously this won't hold true for everyone, but its often is true more times than not. Also remember to value bet, value bet and again value bet.
If you are used to online, bring some music or something to keep you interested between hands. Live will go much slower. Sometimes painfully slow. Do try to pay attention to every hand though, you'll be able to learn a lot about players by watching them.
Main thing is to play your game, watch out for regs and what they do, don't let people intimidate you and most importantly have fun and enjoy it! Good luck sir!