Hi Mindy. When I used to make wedding cakes, I did frost them first with a "crumb frosting" to seal the cake and to cut down on the number of crumbs when applying the final frosting. Worked great!

To make the crumb frosting, I thinned (with water) the same frosting I was going to use to finish the cake. It was almost the consistency of syrup when I worked with it. I also usually froze the cake layers after I applied the crumb frosting. I took them out of the freezer when ready to assemble and frost the cake. The freezing process also helps keep the cake moist. ((sometimes they were in the freezer only overnight)). I hope this helps. Kel