The notes for a short speech -- three to five minutes -- should fit on an index card.
A short speech typically starts and ends with thank-you's -- thank you for asking me here to speak, and thank you for listening -- so there' no need write that out.
Focus on the meat of the speech. It's easy for audiences and speakers to remember things in threes, so divide the speech into three parts.
An index card for a speech on drunk driving might look like this:
Thank you for inviting me here...
Why I care
- story of my neighbor and her family, killed by drunk driver
Why you should care
- every year, drunk drivers kill more Americans than died during Vietnam
- you can make a difference
What you can do
1) reach out
2) speak out
Thank you for listening ...
It shouldn't take long to do the "thank you sandwich" automatically, without notes, and to simply put three parts of the speech on the index card.
When a speaker is comfortable with three bullets on an index card, try giving the speech without even an index card. Boil it down to three points and memorize them.
For this example:
1) Why I care
2) Why you should care
3) What you can do
With some practice, that's all you'll eventually need to carry around in your head.