Stay calm and carry on
Before you book. Be sure you know what the legal requirements are to wed there. Some countries have residency requirements that require you to spend a few extra days there before you can marry, so know before you go! There may also be additional paperwork to complete stateside and take with you, so check with the local consulate well in advance.
Take your wedding dress with you! Don't pack or ship that pretty package, carry it on the plane! (You might even get upgraded when you do.) And be sure to pad it and protect it accordingly, using tissue and at least two garment bags to keep it safe.
Will the room block end up costing you money? When placing a group of hotel rooms on hold at a discounted rate for your group, be sure to discuss the fine print with the property first. Do they require a credit card guarantee for those rooms and you'll be stuck paying for any unused and empty nights? If so, be sure you reserve the right number of rooms, or seek hotels with other hold options for your event.
If you're hosting a destination wedding, plan a honeymoon away from where you wed. Whether that means taking a car across town, island hopping, or packing up and heading to a different part of the world, it's important to get that one-on-one time you may not find at the same property where your guests have decided to extend their vacation.
Consider working with a travel agent. That's right! The days of travel agents aren't dead and they can still help you find amazing deals, educate you about the pros and cons of each location, and plan activities you might not think of otherwise.