One idea for a best man speech is for the best man to spend the weeks before the wedding writing down some of the anecdotes, jokes and quotes he may integrate into his speech. The purpose of all information presented is to make the groom look as good as possible.
The best man's speech should start by expressing gratitude by proposing toasts to individuals such as the bride's parents and groom's parents. He should thank them for raising their children well and then thank the assembled guests for coming.
The speech should incorporate an engaging story that also ties to the best man's support for the marriage. This might include stories about the groom lamenting his inability to find a woman with certain qualities and his obvious joy at having now done so. Another possible story is the best man describing the exact moment he realized how much the bride and groom love each other.
The best man to stay sober before giving the speech. Many are tempted to drink alcohol to be less nervous before speaking in public, but if he accidentally becomes too inebriated, he may say something embarrassing.
The best man's speech should avoid offensive, embarrassing, or controversial subjects, as well as any inside jokes. The best man should keep the speech short and end it with a quote relevant to the wedding.