Let's face it — the planning of a wedding is primarily done by the bride. While it's certainly a couples affair, when all is said and done, the wedding is thrown for the woman who has been thinking about her dream wedding for so many years. The groom often needs to step aside, be a yes man, and make sure the bride is happy and has what she wants for the wedding.
But at the same time, the man has his own responsibilities in planning the wedding, and needs to step up when called upon by the bride, the venue or the families.
The biggest task for the groom is simply be supportive. Compromise may be a big factor in making decisions, but the bride generally gets what she wants on her big day. The traditional list of groom's duties include, but are not limited to, obtaining the marriage license, the rings, the officiant's fee, a wedding gift for the pride, gifts for the parents, and planning the honeymoon.
The groom should help plan out the guest line with the bride, track down missing RSVPs, dealing with family, and staying on top of the rehearsal dinner. While there are other tasks to be aware of and responsible for, the groom's main responsibility is to be supportive and to help with whatever is asked of him. If the bride needs help with the flowers, the food and the venue, the groom should make himself available.
Most importantly, as they say, he just needs to show up on time, and everything should work itself out.