Some seemingly small oversights can make even the best-planned trips go sideways in a heartbeat. Missed documents, packing issues, or simple timing mistakes can turn what should be a relaxing getaway into a stressful experience. The good news is that, with some precaution, most common travel problems are predictable and preventable. Here are some easy-to-make mistakes that can unexpectedly ruin your trips, and some practical ways to avoid them.