Intonation. Every note should be at the correct pitch. While this might seem obvious, it is the most common cause for auditions to be rejected.
Accuracy. Get the metronome beat firmly in your ear before you turn it off, and follow the beat without variation. Play every rhythm exactly as written, and don't leave any notes out. Pay close attention to the articulation, and make sure you take the indicated repeats.
Tone. Strive for a tone quality that is centered, round, warm, and supported. Avoid shrill, blaring, piercing, unfocused, and nasal sounds. Think of blending in with an orchestra. Band members, think of a concert band tone, rather than marching or jazz band.
Anonymity. In many cases, the Evergreen Philharmonic director doesn't know you and has never seen or heard you play. Your audition will be the only input available for deciding whether you can be accepted. You owe it to yourself to make your submission a showcase of your very best playing.
Legibility and Completeness. If the information you provide is incomplete or cannot be clearly read, there is no way to identify you, or to contact you with the results of your audition. This produces the same outcome as if you had never submitted an audition. Take the time to be sure all your information is complete and accurate.
Retakes. Listen carefully to each selection after you have recorded it, and make sure it is up to your highest standards. Don't hesitate to re-record one or more selections if you think you can improve them. Of course, submit only the best take of each selection.
Equipment. Sometimes a qualified student is rejected because poor quality of the recording renders the audition unacceptable. While you don't need to engage a recording studio, or meet professional standards, you should choose the highest quality equipment available, and the recording should be clean enough that it doesn't obscure the good aspects of your playing. If you are using a computer, you may wish to do some research on how to improve the sound quality of recordings. If you're not confident of your equipment or your ability to operate it to your advantage, by all means get someone to help you record.
Mechanics. Before recording your selections in earnest, do some short test takes to determine the best physical setup for recording. In general, a larger room (such as a living room) is preferable to a smaller one, and some sound-deadening surfaces (carpet, curtains, cushions) are helpful in reducing echo. Position the microphone five feet or so from your instrument, and set the bass and treble controls to normal (medium) levels. If available, use manual settings (volume, treble, bass) in preference to automatic settings. Stereo recording is recommended but not required. When you listen to the test takes, make sure the recording volume level is reasonable and there is no distortion of your sound.
Instructions. Sometimes there are a large number of auditions for a section with few open positions (for example flute or violin). Such auditions can be quite competitive, and there might be "close calls" requiring a choice between submissions of essentially equal caliber. In such cases, preference must be given to submissions that most carefully follow the instructions. Your attention to detail is a valuable indicator of your future success.