We have only done one wedding. Everything went well.
My one piece of advise is if you are doing one take spare leads - at least one of each type.
Also physically check, by playing it thorough your PA, that you have the correct lead, not the one that is used in another setting to connect, laptop, iphone, MP3 player to your PA. Phoning and checking that they have the correct lead is not enough let me tell you!!!!!
I have had a bad experiance with a lead (or lack of).