Jehovah's Witnesses only!?

Hello to all my fellow brothers, I just have a quick question that I hope you guys can help me with. Ok so my friend is getting married in 3 months and he has asked me to be his best man. What do witnesses best mans do?. I mean I do know the duties of a best but this is only in worldly weddings. I want to make sure that I don't do anything bad and make Jehovah and my friend upset. Can anyone enlighten me as to what I should do for my friend since I am his best man? Anyone has previous experience, has been a best man to a witness friend or know of best mans in the past?.. I know that worldly best mans give speeches at the weddings and they plan a bachelor's party for the groom. This is something as witnesses we wouldnt do right? Anyways, please if you'd like give me some ideas as to what I should do. I want my friend to have a wonderful time before the big day and of course at the wedding too. Thanks a lot in advance!