I like to come to the wedding rehearsals for my clients if possible. This lets me see exactly how things are going to happen during the ceremony so I can be ready for the shot. Sometimes these rehearsals can be so informal that it is difficult to tell whether something out of the ordinary is going to occur or if a longstanding tradition is going to be enacted.
If you have something unique planned for your ceremony or if your faith requests certain symbolism be enacted, be sure to let me know. More than likely I will be able to capture whatever it is on the fly, but it always helps to know in advance. Last year I had a couple bring their kids up to drop 3 stones into an awaiting holder. They told me it was going to happen and I even got a chance to whisper in the kids ear to "go slow" so I could get several different versions of this moment.
Also, if the person marrying you has certain guidelines that they need the photographer to follow (no flash, no close up photography, areas that are off limits, etc.), this is something to communicate as well. As part of my preparation as your wedding photographer, I will be asking these questions but in case we miss something, it's never too late to speak up.
It never hurts to be overly prepared!!