Add Headings and they will appear in your table of contents.
The following tips have come from past participants and winners:
You might record and preview yourself many times.
Solicit feedback from different audiences: practice live or on Zoom with friends, your advisor, your family.
Less is sometimes more. Consider giving less information and more time to explain. Breath.
Practice speed talking through your presentation. This will help you discover where your "hiccups" may occur.
Practice your transitions, especially the last sentence of one paragraph and the first sentence of the next. Your mouth will form muscle memory that will help you keep moving forward.
Practice your speech in other settings as you are doing other activities.
Recite your pitch as you prepare to sleep at night.
Script out your movements and your pauses.
You can learn a lot by watching the 2020 Council of Graduate Schools 3MT Showcase: