For a start, tune in. Imagine the thought that whatever happens, everything will be fine. The problem is not the problem, but only the minor difficulties that are easily overcome. With the right attitude, you can much more.
If the wedding is about to begin, and the bride's bouquet, no, will save you the nearest flower shop, buy fresh flowers, tie a ribbon and all. This, of course, a wedding bouquet, but better than nothing.
At the time of order rent wedding car, try to correctly calculate the time taking into account possible traffic jams. The fact that drivers often are two orders in a row and after your wedding it can expect a very different place, so after the paid rental period, you can just ask to see the car, and the entire wedding procession will be in the middle of the road. So it is better to think in advance the possible options.
No photographer - not a problem. Ask a few friends with nice cameras to take pictures from different angles. Good pictures can be selected from a large number of footage.
If you forgot the rings...Hard to imagine, but it happens. If you have time to check, ask someone their guests to run to the nearest jewelry store. You can buy some simple and cheap rings and use them symbolically.
In case something happens with the dress, it is better to have a needle, thread and tools, quickly eliminates stains. All these accessories should be in her purse, relatives or the witness. Make sure in advance.
Wedding event long, and legs can appear corn, so it is also better to have a "kit" with a band-aid and all the necessary first aid.
If guests at the wedding, to put it mildly, carousing, and celebration threatens to turn into a scandal, someone from staying in adequate condition to keep an eye on revellers or, in extreme cases, send them home.