How can I improve my speech delivery?

Answer 1

There is nothing that beats practice, practice, practice. Chose topics you know well.

Answer 2

You improve by:

1) Practice. I know that that word strikes dread, but think about Olympic athletes who spend 10,000 plus hours on practice. They became world-class athletes by practicing.

2) Seek input. Ask friends for feedback or ideally get a coach who can give you tips on delivery and structure

2) Choose topics that you are genuinely interested and knowledgable about. People are more effective when they are excited about their topic and aren't worried about getting a question that they don't know the answer to.