Planning the bachelor party is just the beginning. The best man should do all he can to take weight off of the groom’s shoulders, such as handling any (or all) of these tasks.
During the Wedding Planning
Help the groom choose tuxes.
Organize groomsmen’s fittings. Keep everything on schedule.
Plan and give the bachelor party. Keep track of who’s invited, who’s coming, where everyone will stay, and what activities will take place. Stay on top of the costs, making sure each attendee pays his share.
Help arrange wedding accommodations for out-of-town groomsmen.
Organize a groomsmen’s gift for the groom. This can be presented at the bachelor party.
Keep groomsmen apprised of any changes in scheduling.
Shortly Before the Wedding Day
Organize the couple’s departure from the reception. If they or you will drive, consider decorating the getaway car (tastefully); otherwise, arrange and confirm a limo or other transportation.
Confirm honeymoon travel reservations, if the groom wishes.
At the Rehearsal and Rehearsal Dinner
Attend the rehearsal. And pay attention—you may need to help others remember their places and schedules later.
Organize who will be giving toasts at dinner. Set the order.
Give the second toast, after the father of the groom (if the groom’s parents have paid for the dinner). Or, if he is not speaking, give the first toast.
At Home, on the Wedding Day
Help the groom get dressed.
Get any payments for the wedding officiant, musicians, or other participants from the groom. Have him put the payments in individual sealed envelopes with each recipient’s name on one.
Take charge of the wedding ring(s). Stow them somewhere safe (like your vest pocket).
Make sure the groom has the marriage license with him. And get him to the wedding venue on time.
At the Ceremony
Take a head count. Make sure all groomsmen are there on time, dressed appropriately, and ready to seat guests, if they are ushering.
Make sure all groomsmen have boutonnieres, if using, attached properly to their lapels. Get help from the florist or wedding coordinator, if necessary.
If there is a ring bearer, check in to make sure the child knows what he needs to do. Attach the rings to the pillow.
Stand by the groom’s side while waiting for the ceremony to start.
Hand the groom the ring(s) if there is no ring bearer.
Escort the maid of honor down the aisle when the ceremony concludes. Then return to escort the mother of the bride.
After the Ceremony
Deliver the fee envelope(s) in private to the officiant and any others.
Sign the marriage license as an official witness.
Drive the couple to the reception if there is no limo.
At the Reception
Act as a host. Welcome guests, mingle, and make introductions.
Organize groomsmen for formal photographs.
Organize who’ll be giving toasts. Determine the order—and give the first toast.
Dance with the bride and the maid of honor. You might expect to dance with the mothers of the bride and the groom also.
Help the groom change into honeymoon clothes, if the couple is leaving directly from the reception.
Take charge of the groom’s tux and return it or have it cleaned.
Take charge of gift envelopes to hold until the couple’s return.
Have either the decorated car (with the couple’s luggage stowed inside) or a limo waiting to take the newlyweds from the reception. When they’re ready to leave, help them make their escape.