Tasks the groom can handle

The planning of the wedding, from guest list to gift registry, should be
a partnership, but often the bride takes on most of the planning
duties.

Set up a spreadsheet Include names, addresses and phone numbers of service people and those who will be part of your team.
Store purchase receipts and confirmations.
Check marriage requirements, such as licensing.
Choose the best man and your other groomsmen.
Shop for gifts for the groomsmen.
Buy a wedding gift and card for your bride.
Scout wedding bands for you and your bride.
Choose suit style for yourself and the groomsmen, and arrange fittings.
Write your thank you notes for gifts received from your side of the family.
Put an honorarium or fee for the service officiant in an envelope and give it to the best man for delivery immediately after the service.
Prepare a speech for the reception. (Don’t forget to thank the parents and gush about your wife.)
Go over song selections for your first dance.
Arrange transportation to both the service and reception for the bridal party.
Research honeymoon options and prices.
Supervise getting travel requirements, such as passports, immunizations and blood tests, if required.

Your best man likely will be your best friend or perhaps your brother. But there are other considerations:

Be certain that you choose someone who has the time, energy and interest in taking on the obligations.
Do not choose a person who is unreliable or who is insensitve to the audience and will embarrass you or your bride when he makes the toast at the wedding.
Don’t be coerced into choosing the bride’s brother unless he happens to be your best friend. The choice should reflect the close relationship between the two people.
It is appropriate for a man’s father to be his best man and not unusual for the groom’s honour attendant to be a woman.