The alarm rings. You squint at the clock. Your first bowel-loosening thoughts are of a car that won't start, a lost ring ... and a lost friend. God, you will become a living joke. Will your new home be in the Andes or Outer Mongolia? You rush to the loo ... the 7.35 is going to be half an hour early today. As you sit (I said sit) there, you ask yourself why you ever agreed to do all this. Abseiling down the north face of the Post Office Tower would be preferable. You get up from a warm, sticky seat, paper in hand. It won't be the last time you do this today. In less time than it takes Britney Spears to get married and divorced, you will be rising from another sweat-drenched seat ... this time with your speech in hand.

Get to grips, man. If you're getting a bit worked up, your mate is probably wishing he'd invested in a family-sized pack of Andrex ... and on a 'Buy One, Get One Free' deal. Reflect for a moment on the wise words of Mr Kipling: 'If you can keep your head while all about you are losing theirs ... it'll be a piece of cake.' Some grooms are totally relaxed about the whole thing. The other 99.9% are not. If you can convince the groom to seize the moment and actually enjoy himself, you will be hailed a hero for years to come.

BEFORE THE WEDDING

Okay, this is the big one. Knock on his door, or phone him, to make sure he's surfaced. Ten minutes later, repeat the procedure to make sure he hasn't retreated to his sack. Throughout the day it's likely that the poor lad will be displaying some or all of the classic symptoms of Pre-Nuptial Groom Disorder (PNGD): severe hand shaking, adrenaline rushes, dry-mouthed terror, nausea ... and a sudden desire to join the lads on Craggey Island. Reassure him that this is quite normal. This is going to be a day to remember... and for the right reasons.

Phone a friend

Check that the chief usher has everything under control. Ask him to contact his fellow ushers to confirm none has gone awol. If there is to be a pre-marital drink, they should be reminded where and when it will take place. Remind the bride's family that you're there to give them all the last-minute support they need. Meek, mild-mannered Clark Kent will become a man of steel. Give the belle a bell to confirm you'll call round to collect the buttonholes (and the Order of Service sheets and Wedding Day Schedules, if you haven't already). Pick up any last-minute telemessages, cards, e-mails and she-mails to be read at the reception.

Trinny and Susannah

Traditionally, you are supposed to act as a fashion guru as you help the groom get dressed for his big day. In practice, you just need to tell him how wonderful he looks, get him to check his flies (kneeling in front of him could be misinterpreted if the bride's mum suddenly bursts in) and make sure there's no dog poo on his shoes. Keep the big man busy by getting him to check he has packed everything for the honeymoon. Make sure you've got all you need for the rest of the day: clothes, accessories, your speech, dosh, plastic, legal paperwork (including licence or certificate of banns) ... and a crate of Valium. Double check and then treble check. Today is not an ideal time to drop a bullock.

Lord of the Rings

It's cliche time. Take care of those rings (or the ring, if the chief bridesmaid is taking care of the bride's). It may not be on the same scale as protecting Frodo against Sauron and the rest of the baddies, but lose them and you'll be as popular as the Glazer brothers at Old Trafford. Keep a substitute ring in your pocket, just in case. Anything ring-shaped and sized will do ... even a Hula Hoop. If it's not needed, it can be used later to bribe any unruly pageboy or young bridesmaid. I find it generally takes more than a Hula Hoop to bribe an older bridesmaid ... but you could try.

Get him to the pub on time

It is common practice nowadays for all male attendants to get together with the groom for a final pre-wedding pint of Dutch courage. It is best to choose a hostelry within walking distance (not staggering distance) of the venue for the ceremony. The time for gentle argument and subtle persuasion is now past. If he's still suffering from a bout of PNGD, bundle him into the back of your car and activate the childproof locks. Then frogmarch him into the pub. Once he is securely chained to his seat, phone or text the bride's dad to let him know all is well. Convention demands the injection of a little gallows humour at this stage. And come on, Mr Motivator, you've got a captive audience here. Get the lads really psyched up for the main event.

AT THE WEDDING

And so to wed. The ushers should be at their posts at least half an hour before the ceremony is due to start. You and the groom need to arrive about ten minutes later. If you are given the opportunity, pay any outstanding church or registrar fees before the service (it's a bit of an anti-climax afterwards). Get someone to take a snap of you shaking the groom's hand (or his neck, if PNGD persists) as you are about to enter the building. Turn your mobiles off and take your places in the front right pew.

The big wait

This is another stressful time for your mate. He's probably more nervous than a moggie in a room of pitbulls. Help him out. Provide his moral support. Mutter reassuring words. Keep chatting away ('Did you find Marx's vision of a post-capitalist state persuasive?', or perhaps, 'Have you heard the one about the nun and the bicycle ...?'). The last guest to arrive will be the bride's mum (or guardian), who will be escorted to the inside left position by the chief usher. You will be prompted to stand shortly after the bride arrives. Glance back to make sure it's the right girl, then step forward and stand a pace behind and to the right of the groom.

The ring

Keep the ring (or rings) in your front pocket, not on your finger. You may get £250 for a camcorder calamity, but is it worth the public humiliation of the spectacle of a bride and groom tugging at the ring, while their parents are violently pulling you in the opposite direction? It is? Oh, alright then.

Signing the register

The deed is done. Now they just need a few autographs to sell on e-bay. It is usual for the bride and groom and two of the parents to provide illegible scrawls. Occasionally, however, the best man and chief bridesmaid are asked to sign on the dotted line.

The traditional order of departure from the church is:

• Bride and groom
• Bride's father (or guardian) and groom's mother (or guardian)
• Groom's father (or guardian) and bride's mother (or guardian)
• You and chief bridesmaid
• Rest of the world

While the paparazzi may have decided to give this one a miss, there are still likely to be more digital cameras, camcorders and video mobiles clicking away than on Oscars Night. So keep smiling ... and don't pick your nose or scratch your bum.

Photo opportunities

Unless the happy couple have made an exclusive deal with OK! or Hello!, it's pretty much a free-for-all when it comes to taking postnuptial pics. This is brilliant as it gives you the chance of scrounging loads of snaps to make up a surprise wedding album while they are away enjoying sea, sun and ... sand. Professional photographers will know all the best local backdrops for their snaps (recently dug graves are not to be recommended). They will appreciate it if you can help make sure the right people are in the right shots. Otherwise for years to come everyone will be wondering about that mystery guy in the back row ('I thought he was with your family' ... 'I thought he was with yours'). Once all the traditional wedding photos are in the can, get a few informal ones. The bride lying across the arms of the groom, you and the ushers is always a favourite ... especially with horny teens.

It's time to get the show back on the road. Put on your most assertive voice and announce that the bubbly should be nicely chilled by now. Tell any stragglers that the last to arrive pays for the first round. That should speed things up. We have a convoy.

AT THE RECEPTION

The receiving line

This is an outmoded wedding day filler that deserves to be consigned to history. People wait in line as if to pay their last respects to some poor old sod lying in an open coffin. The ensuing human traffic jam makes the M25 look like an easy ride. The traditional order of handshakes and pecks on the cheek is as follows:

• Bride's mum and dad (or guardians)
• Groom's ditto
• Bride and groom

Some couples also want their best man and chief bridesmaid to be at the end of the line. If you are to be included, get the ushers to guide people to the shakeathon. If you are not, it's down to you. If the reception is less formal (or more enlightened), simply guide people towards trays of champagne (and soft drinks). No one will complain about that.

Update your speech

Take it easy on the booze and think about one or two of the more amusing or poignant moments of the day so far. Could you make a passing reference to them in your speech? That would add a bit of topicality and give the impression that all your words of wit and wisdom are spontaneous. In reality, of course, 99% of them will have been planned, rehearsed and fine tuned well in advance.

Stand and deliver

It is usual for speeches to be made after the guests have eaten. However, some couples prefer to have them before the meal, especially if some of their friends and family are known to be a little rowdy after a drink or ten. If there's no toastmaster, you will have to do a bit of MC-ing, announcing when dinner is to be served and the order of speeches. Once you are all ready to strut your stuff, stand up confidently and jingle a spoon in a wine glass to get people's attention. It's showtime.

FINAL DUTIES

The pressure's off now. It's time to relax and have some fun. Pour yourself a mug of Dom Perignon ... you deserve it. Greet your adoring public. Carry a gaggle of admiring guests along the rounds to catalyse inter-table introductions and then deposit them in your wake as you move on.

If music be the food of love

The newlyweds will be first to take to the dance floor. When Robbie gets to the second chorus (you know, the contraception bit: 'She offers me protection, a lot of love and affection'), you and the chief bridesmaid should join them. Before long everyone else will be bopping away alongside you, arms waving rhythmically overhead.

When knee sliding begins, you know it's time to make your temporary excuses. Make sure all the penguin suits have been collected and hide all the pressies from that dodgy-looking geezer at the bar. The bride will have made a mental inventory and will not appreciate it if one of her five George Foremans, seven toasters, or 11 steak knife sets is half-inched to the accompaniment of Thief in the Night.

Okay, it's another cliche, but decorating the car is a wedding day ritual that simply must be observed. Spray 'Just Married' across the rear windscreen, tie tin cans to the rear bumper, or attach streamers to the wing mirror and balloons to the aerial.

Remember that bridesmaid you spotted adjusting her dress five hours ago? She seems a little merry now. Open another jeroboam. This is the time to make your move ...