Your "main guy" has chosen you to stand by his side on one of the most important days of his life, so you need to make sure that your part in making that day a succes is fully and well played out.

Apart from the obvious and expected organizing of a very "fun filled" bachelor's eve party or stag night, there are other things that the best man has to do.

So what are you really expected to do apart from trying to call off the wedding before the d-day so you don't loose your main man to a chick… just kidding. 

Here are some of the things that are expected of you as the best man:

Before the wedding

Organize the bachelor party. You can enlist the other groomsmen to help you out -- most guys don't mind this duty! If you are worried about finances, just split the cost among everyone who attends the bash.

Serve as the groom's personal aide and adviser during the planning process.

Help the groom choose and rent (or buy) wedding formalwear, and coordinate the other groomsmen's wardrobes. Organise fittings for the groomsmen and make sure the mens wardrobe is ready on time. 

If the groomsmen need to be at a certain location for the wedding, you may be expected to arrange accommodations for them (you need to take into consideration those that stay nearby and those that live out of town and out of the country).

On the wedding day and during the wedding (ceremony and reception)

Help the groom get ready and get to the church or ceremony venue on time.

If there is a ring bearer, make sure that he has the rings safely kept (or keep them for him till he is needed) and that he knows what to do at the ceremony.

If there isn't going to be a ring bearer, stand beside the groom at the altar and keep the bride's ring until vows are exchanged. Find a safe place for the ring (and triple check that your pockets don't have holes) -- you don't want to fumble around when it's time to whip it out.

Sign the marriage license as a witness after the ceremony, along with the maid of honor (if you are asked to do so).

Ensure that everyone has transportation to the reception venue.

Assist photographer in organizing guests for the wedding shoot.

You may be announced with the maid of honor when the reception begins, make sure that you are available have a happy smile on your face and walk in with her to the reception venue (even if you don't like her).

Dance with both the honor attendant and the bride during the wedding party dances.

Give the first toast to the bride and groom at the reception. This is your biggest -- and probably most frightening -- duty.

Collect any gift envelopes guests bring to the reception. You may be asked to deposit them in the couple's bank account or at least to keep them until the couple returns from their honeymoon.

Drive or drive with the couple to the wedding-night hotel or airport after the reception. If you have a feeling this may not be possible, make sure that you have made the necessary arrangements for a driver to drive the couple away from the reception venue.

After the wedding

Return any hired clothing and accessories.

Make sure that any items (gifts, clothes, etc.) that was left in your care for the period of the wedding is returned on time and in good condition to the family of the couple or to the location they where taken from.

NB: The wedding will be over in the blink of an eye, so remember to enjoy yourself at the reception. After all, you're there to celebrate the happiest day of your best friend's life.

Resources: weddings.theknot.com

                  hitched.co.uk
                  realsimple.com
                  artofmanliness.com