Getting To The Embarking Port

The only important thing:
Whatever you do, choose the ship that embarks from a place that is nearest to you, for God's sake! You can get there by car in a few hours, and driving is a lot less of a hassle then all the airport mess you will have to go through otherwise.
If you've already messed this one up, then, please, DON'T BOOK CRUISE AIR! First, with a little effort, you'll easily beat their prices. Second, they usually choose lousy flights, and you can end up getting to your embarking port only to find out that there's no ship waiting for you. Yeah, happened before.
Actually, the best cruise air I've experienced when taking the Caribbean excursions was when I was going with Carnival. But still, I don't recommend it.

An extra tip: pricier staterooms include more goodies. With Carnival Cruise excursions one of them is priority embarkation. Think about it... having in mind that the cruise ships are made for a few thousand people ;)