As Redknightt mentioned, announce your intentions - there's something called "string betting" where you put some chips out then put more out. You have to put the entire call/bet out at once or you're stuck with the initial bet whatever it was. Announcing what you do is the best defence against being caught by this or by accidentally miscounting your chips. Just say "Call" or "1500 total" or whatever before you put the chips out. If you put the wrong number of chips out you'll be allowed (required, really) to correct it.
It's not required, but definitely to your advantage to not look at your cards or get your chips ready to bet until it's your turn to act. I've seen a few new live players do this. Knowing what you're about to do gives a huge advantage to the people to your right.
Don't mess with a phone or ipod or whatever when you're waiting for the action to come around to you. It tends to piss people off when they're constantly having to wait for you to finish up before you act. In fact, don't even bring those things with you.
Put something on top of your cards right after you get them. Most people use a spare chip, some bring some novelty item of around that size with them. In many casinos
if someone mucks their cards and they hit yours by mistake, your hand is automatically mucked as well. The chip protector keeps this from happening.
In general, just try to chat up the other players and dealers. If they like you they'll be more likely to help you out with the mechanics.