Practice each story out loud at least times. Time yourself. The target is under minutes.
Record yourself and listen back. You'll catch filler words, vague statements, and places where you say "we" instead of "I."
Do at least mock interviews with a friend. Have them ask follow-up questions. The more you practice interruptions, the less they'll rattle you.
Common mistakes to fix: stories too long (over minutes), no quantified results, starting with sentences of context, and saying "we" throughout the Action section.