Good Day To You,
As I am always writing speeches nowadays, it’s always good to review the basics of speech structure and story writing. The main difference is, your material will be presented by you verbally instead of read, So I prefer speech writing because I don’t really worry about the exact grammar but concentrate on making points simple, well explained and entertaining.
Another one : http://www.wikihow.com/Write-a-Speech
Each article has excellent tips if you ever have a case of Writer’s Block.