At the wedding reception, there will most likely be a seating plan. You can check this and then you'll have an idea where you will be going once inside the room in which you will be eating.
If it is a formal affair, there will be a greeting line or line-up. This is an opportunity for the couple and sometimes parents and even bridal party to greet guests personally and thank them for coming. Its handshakes and hugs.
After not eating for hours, you are approaching tea time and depending on the time of year, possibly darkness. It is now it is time for the Wedding Breakfast. Clever eh?
The couple will be introduced and all the guests greet them into the room. Once they are seated, everyone else can sit down. You can usually expect 3 courses + coffee and champagne and 3 speeches: Father of the Bride, Groom and Best Man, along with a few gifts to key persons. The champagne is for toasts during the speeches.
There may be disposable cameras on the table, for you to snap the other guests. It's a good idea to make use of them but don't forget to charge the flash before making a picture. Then keep your fingers away from the flash and the lens when making your picture.
You may well be asked to fill in a guest book. If you are not the kind of person who can make something up on the hoof, you may wish to have a sentence or two worked out in advance, perhaps saying something positive or just wishing the couple good luck and happiness.
During the meal, circulation time or in the evening, try and spend some time with the couple. They invited you so clearly want to spend time with you. All too often, everyone thinks the couple are too busy and try and give them space. In the end they can end up feeling lost at their own party. The couple may circulate during the meal but they may feel too overwhelmed themselves. Remember they are the same people you normally see in jeans and a t-shirt and now they are sandwiched between parents on the top table and would probably appreciate you giving them a temporary rescue of a chat about the stag or hen do, their honeymoon plans or just whatever it is you normally do together.
On the whole, most couples prefer to be the only ones on the dance floor for at least the first half of their first dance, so if you have children with you, please hold them back between the time the DJ or entertainer introduces the first dance and a point when they invite other people to join them on the floor. This is not the case 100% of the time and some couples can't wait to not be the only ones on the floor. It's worth checking if you think you'll have a job holding the kids back.