I took my first professional audition when I was 16. I was not even close to being ready to "win," but to my instructor, my preparation up until that time seemed to be satisfying enough to take the audition. Though I did feel very prepared going into it, when I got on stage my nerves took over, and I performed horrendously. From then on, I knew that nerves were the biggest challenge to overcome before I was ready to win an audition. It took about six years for me to figure out what I had to do to overcome those challenges, and I decided to take auditions throughout that period.
Before I felt comfortable taking an audition, I made this checklist for myself. I will stress that your technical facility should be at a certain level in order to achieve these standards. Each time you take an audition, strive to increase this level further than the last audition taken. Be patient through this process and don't feel as if you have to hurry to be at a certain level. Take your time, and work diligently towards these goals.
Excerpts should be note perfect- If you can play the excerpt note perfect at least ten times in a row, it is ready for the audition. This increases your chances of you correctly executing it at the audition.
Everything must be in time- While performing the excerpt, no unintentional pushing or pulling of the tempo should occur, at all.
Everything must be in tune and have consistent timbre- Intonation should be as flawless as humanly possible, and you should develop your ear to hear even the slightest change in intonation during performance, as well as your reaction time to correcting that change. This also includes the color or timbre of the notes. The color and quality of the notes should not change unintentionally, but remain consistent throughout each piece.
Every sound must be appealing and appropriate- The sound must match the character and style of the excerpt, and be consistent throughout the excerpt.
Do at least 1 mock audition- You don't want to go into the audition completely blind, so do at least one test run before you take it. This allows you to observe how nerves affect your playing, and assess how you can adjust when they arise.
Only after this list is completed should you take an audition, especially if your intent is to advance or even win. For some people, completing this list alone will be enough to create a strategy for a successful audition. For others like myself, it will not be enough, and I learned that only by taking the audition. I would not have learned how nerves affect my playing unless I took the audition. I tried doing more mock auditions, but they didn't feel anything like actual audition. So, I spent the bulk of my preparation finding ways to emulate that feeling. I did find some methods that worked, but I could only test them out at the audition. Unless I did the real thing, I would not have known how to prepare for it properly. I took my time and stayed as patient as I could have while searching for my personal strategy, and I encourage you to do the same as you prepare to take auditions in the future.