My DD had an Audition for RB two years ago which gave us a great understanding of the process. We were very under prepared. The following year my daughter auditioned for another school and was successful mainly because we were armed as a family with the experience of the first audition. The success at the second time I feel was due to a reduction of the pressure on my daughter as we had the attitude that the audition was a "look in the door" of what happens inside a performing arts school. Essentially interview / audition practice. She relaxed, enjoyed herself and smiled which I think made the biggest difference over her technique. A happy child with a smile I think is the most important. (Just an opinion). Good luck.
