Want to Know What to Say in a Best Mans Speech

I have been going to a lot of weddings lately. I think I am just at that age where all of my friends are getting married. I have been asked to be the best man in an upcoming one. I am honored and I want to make sure that I do everything right. I want to know what to say in a best mans speech. I know that it is something that is important and that people really listen to. I want to make sure that I say all of the right things and make a lasting impression on my friend and his guests.