Help with my singing audition?

so i have decided to audition for chorale at my school. i am in 10th grade but i havent really done much singing since 8th grade. i was just going to do concert choir next year, but chorale always needs more altos and a few people in chorale told me to. i am going to sing either "amazing grace" or "the kerry road". do you have any advice for an alto singing these songs or any advice on how to improve my technique? i used to be a pretty good singer but i lost my technique after not singing for almost 2 years. thanks!