Many travelers consider all their flight-planning work done once they buy a plane ticket, and they don’t think about it again until it’s time to fly. In most cases, that’s a recipe for trouble. There are many things that could go wrong and ruin your trip long before you arrive at the airport, and paying just a little attention — I call it “gardening” your reservation — and knowing how to handle those issues in advance could prevent a travel disaster.

Let’s begin with the simple things. As you may have discovered, sometimes there are no seats available for you to select at ticketing. That could be a result of overselling the cabin, or the only seats left may require an additional fee. Many fliers simply leave it at that, hoping for a seat on the departure day…