High expectations can kill you. Remember that nothing is perfect and something at some point will fall apart on your special day. If you have a plan B ready then it won't seem like such a catastrophe.
Delegate, delegate, delegate. Find a good wedding planner or split the jobs up amongst the wedding party. You don't want to miss the toast to the bride because you were negotiating with the caterer in the kitchen.
An open mic can kill the buzz. Sure, it's nice to have a couple of nice speeches but if good old Uncle Charlie blabs on for an hour about your first birthday, or if your best friend Cindy tells the story of when you snuck into the strip club and peppers it with inside jokes then you are definitely going to kill the momentum of the evening.
Have lots of diversions for mothers and future mother-in-laws. Keep them busy with the little things so that they don't get their mitts into the things that matter. I suggest multiple spa treatments in a country villa.
And last but not least, remember to have fun. In a few years you will never remember that the orchids for the tables didn't show up or that your new sister in law pronounced your name wrong. Having fun means fun pictures of you and your brand new husband smiling. And that will last a lifetime.