Advice ?

for the audition: try to arrive early so you have time to relax and prepare for the audition.
try to memorize your first few lines so when you are performing you are 'getting into the story' and not reading from the script.
try to avoid covering your face (maybe you can put the script down) so the casting directors can see your emotions and expressions.
try not to look at anyone else in the room (including the person reading the script) and pay attention to your character.
try not to over do!!!! make it realistic and believable
when closing the piece, hold your last look for a second or two then release or wait until the director says cut.

As general acting advice, try to stay in your character even if you mess up just keep going and don't stop (unless your told to), also when your acting try and commit to the character as much as possible, an easy way to do this is to think about what you and your character have in common and try to put that forward so that character truly comes to life. If you really want this than you really have to stand out, but when trying to stand out don't go over the top and most of all just be yourself so they really know what you are like.

hope this helps and good luck for your audition :)