In most weddings there might be a cocktail reception, with standing tables available for guest to mingle and have a few pre-dinner drinks. If this is the case, it might be advisable to close the doors to the dinner hall to encourage the guests to make full use of the cocktail reception.
There should be ushers at the entrance to direct guests to the registration table and thereafter, to the bar or even the photobooth, and to prevent them from entering the dinner hall before all the preparations are completed. Friends who are in charge of registration should also make it a point to suggest to the guest when they sign-in to get a drink and a photograph before dinner commences.
This would help to avoid a situation where the cocktail reception area may appear to be deserted.
2. Speeches
Always do a sound check for everyone who will be going on stage, whether it is the live band, the groom, the best man, the emcees, etc. This will help the individual familiarise themselves with the proper microphone technique. Some mics require the speaker to speak directly into the mic, some mics need for there to be very little distance between the mouth and the mic itself, or that you may have to calibrate the volume of your own voice so as not to deafen the people sitting closest to the speakers.
Ensure that when speeches are delivered, the food aren't. There is nothing more disheartening for the best man to work up the courage to stand in front of a couple hundreds of people only for 90% of them to ignore his speech because they are being served suckling pig.
Lighting is equally important in such segments. Turn the lights down in the main hall and have a spotlight shining on the stage to focus the guest attention towards the speaker. This also helps the speaker to not be distracted by the ongoings below him as he would not be able to see beyond the notes on his podium.
Also, always remember to give the appropriate thanks to everyone who has helped you on your wedding day.
3. Bridal march-ins
Will the march in consist only of the bride and groom? Will they be preceded by their parents or best man and maid of honor? Will there be a pause in between the different couples, and if so for how long? I would suggest that there will be two different music for the "other" couples and the bride and groom themselves. Also, think about whether you want your guest to be sitting or standing up when you march in. Both have the supporters and detractors so it really depends on the wishes of the bride and groom.
If you intend to use party poppers please inform the restaurant/hotel beforehand. Most are happy to allow for that but some charges additional cost for cleaning up after!
4. The toasts
Prepare a list of people you want to be on-stage for the toast. Do not leave any of the important people out, so plan this list beforehand. You will also have to ensure that there are sufficient champagne glasses on the stage for distribution to everyone up there. If not, have one of your mates stand by with a tray of emergency drinks.
5. Delegate!
Appoint someone who will be the floor manager for the evening. The floor manager will be responsible for coordinating the entire evening from when to inform the restaurant manager the correct time to serve the first dish, to ensuring the bride and groom are ready by the entrance for the march in. This person must be as familiar with the itinerary as their own backhand, and will also be in charge of the videos and slideshow presentation, or rather, making sure the restaurant/hotel's video guys doesn't screw up the sequence of the videos.
Also have someone in charge of the even distribution of alcohol so you do not find yourself staring at 3 empty beer barrels after only the second dish.