If you are attending weddings prior to your own don't be afraid to ask the caterer or catering staff for a business card. This can help you keep track of good caterers that you have already tested their food. Make a note of what you had and what you liked of the service on the back of the card.
If the caterer indicates that a particular dish does not work in the menu or will be difficult to serve or prepare in the give facility, be sure to listen. Remember that the caterer is a professional and should be able to let you know if something you are suggesting will not work.