I worked as a makeup artist in college and have done at least 40 to 50 weddings in my day. Seeing as this is a destination wedding forum, I'll assume most of us will be in a warm humid climate. So, my big thing is to use a very light moisturizer don't use a moisturizer or foundation that is humectant. Humectants pull moisture into the skin, and you could get dewy really fast on a humid day. Just use a light moisturizer even something with a little silicone. You can mix your moisturizer with concealer to even out skin tone and any imperfections. (thin layer is better than thick) I like to buff powder foundation lightly into that on top with a large blush brush. Go light, you shouldn't need much. You can blot with a kleenex to remove access.
Some think this looks stark, and it does cause you have no shape to you face. Once you add bronzer and blush it is really very pretty.
I worked for a number of different companies and MAC Select Cover Up Concealer and Studio Fix or Mineralize are by far my favorites, they are beautiful and cost effective. Not to mention you can go into the store and have them show you how. As for bronzer my favorite is CK Calvin Klein, they have it at Sephora.
With whatever you go with, blot away excess sweat and makeup before you add more during touch ups. This will keep you from a heavy face at the end of the night.