Don't try real hard to act like you have played live before: you'll end up putting too much energy into it that could be used for better purposes like actual concentration and analysis. I know everyone naturally wants to "look cool" at the table, but I think you will be better served by announcing right at the start out loud to the table that this is your first time playing live. People will misinterpret your statement to mean that it is the first time you are playing poker, even though you may have a ton of online experience: that's good, let them underestimate you. If anything, you might find it's actually fun to play up your "inexperience" a bit more than it actually is.
And remember: a single over-sized chip without a declaration first will be considered a call, not a raise (if someone bets $100 and you toss out a single $500 chip without saying anything, it's a call: say raise first, or put out more than one chip if you want to raise).