When you enter into the booth for an audition, you want to be as prepared as possible, and there are a number of things you can do to get to that place of readiness.
First: the script itself. You may not get to see the sides until you get to the actual audition, (or if you have a home studio, the day of) but you should always ask to see if they're available early, downloading them from the web or having them e-mailed to you. If there are specs for the type of delivery they're looking for, find out what they are, but take these with a grain of salt. Often, the ad agency isn't exactly sure what they're looking for. They may have an idea, but your unique interpretation of their script may completely change that idea. My advice is to take the specs as more of a springboard from which you can try out your own ideas. You should do one "their" way and another take with your own unique slant. The two-take audition has worked well for me.
Second: you are going to need to make that piece of copy your own, giving it your own unique reading. The first thing you should do is to read through the copy, not just once but a number of times. You should read for comprehension, for attitude, for any words or ideas you are unsure of, and make sure that you are reading out loud, so you can hear your voice interpreting the copy.
Some people make the mistake of reading the copy silently. Then, after the audition they're upset that it didn't come out the way they had "heard it in their heads." That is because they didn't take the time to make it real, to bring it up to performance quality before they went into the audition booth.
Third: it's also important to make your read a physical one. A lot of folks just starting out have the notion that they can simply get up in front of a mic with their hands behind their backs and let their voice do it all for them. But as anyone who's in the business knows, you can't make a piece of copy truly come to life without getting your body into it. Use your arms, your hands, your torso and your face to express the attitude of the script. It is the body, after all, that really knows about feeling and emotion; your voice is the agent for that expression. When everything is working seamlessly, you raise your read to the next level. The mind helps us analyze the script but it's our physical being that embodies the truth of the words on the page.
Ok, now go for it!
David Rosenthal is the founder of Internet Voice Coach