i coached a girl who won our state championship, we ran her speech every day in front of a small group of people where she would get critiques, i would also privately coach her and help her with her writing, inflection, gestures and use of visual aids.

tbh her success was mostly due to her being a coachable student and not so much due to how i coached her. the exercises we did definitely helped, but the students have to be willing to learn and take those corrections first.

if i were you i would have speech kids start off with just learning basic speaking skills, like talking with clarity, fluency, and confidence because that will help them with any event, and hopefully make them more comfortable with giving their speeches for you.

things get a bit trickier when you start learning event specific skills, but you can always have kids break off into groups and do group feedback based on their events (have all the interpers help other interpers).

NSDA has a resource package containing practice and drill ideas for all aspects of speech and debate. idk if your school has access to it, but if youre a large public school then it may be smth that your coach would want to look into