How do i give a good speech?

Prepare your speech in advance.

Dress nicely.

Practice your speech in advance.

Speak slowly and clearly.

Look at your audience.

If you are standing, don't slouch, but also don't look stiff. It's okay to move around a bit.

Make a lot of sounds that sound like you're clearing your throat; wave wads of cash around but don't let anybody have any; and then get in a tank and start invading everybody.