Introducing your boyfriend or girlfriend to the parents (or friends for that matter) can be very nerve wracking. You want to make a good impression for multiple reasons. You want the parents to like you obviously and you want to make your significant other proud as well. Here are some good things to remember in these types of situations.
--Pump your b/f or g/f for information. Find out ahead of time what type of get together this will be and who will be in attendance. Get the run down on the different family members if its going to be more than mom and dad. Especially if anyone is sensitive to certain topics be sure and avoid those. And its worth noting that traditional manners like using Mr. and Mrs., etc. go a long way too.
--Do NOT pull out your cell phone. Unless there is some critical piece of information you are waiting on (we're talking life changing stuff here people) you should not be pulling out the phone to see if you have a text or to check the time, it's rude and it makes it appear that you have somewhere else you'd rather be.
--Try and think of some questions you can ask at dinner or during the mingling to show that you are genuinely interested in getting to know people. Sometimes shyness or being unsure can be misconstrued as disinterest so even if it's challenging try and prepare of couple of questions or comments that will communicate your interest.