I have been Best Man 4 times and I think that is it for me and Groom once.
Still think the Best Man Speech is easier than the Groom Speech.
A nice finish is advice for the Bride and Groom on their Married life.
Women are like Wheelbarrows hard to push but easy to upset.
Men are like kitchen floor tiles. If you lay them right the first time you can walk on them for the rest of your life.

Best advice plan way ahead and think of good stories you had with that groom adding in your own style / humour.
Use Cards as reminders to help you with the speech. Best not to read from a pre-written script.
Guests want to be entertained and are on your side. Try to enjoy the occasion and get an early laugh.