While reducing your emissions should always be your first priority, offsetting is basically a way to press tare on your environmental impact. You can donate money to initiatives that take carbon out of the environment—like tree plantings and renewable energy projects—to balance out the carbon you're putting into it with your daily routine. Offsetting your flights is a good place to start, since plane travel is a major emitter but one that most of us can't realistically give up altogether.
JetBlue's director of sustainability, Sophia Mendelsohn, said it best when she told mbg: "You can say you're never going to fly just like you can say you're never going to eat a sweet or a carb in your entire life. But the reality is we're all human. Offsetting emissions is like going to the gym. We are all going to treat ourselves from time to time, and that's totally fine, as long as we balance it out. For just a couple of dollars, you can effectively undo a lot of the impact from your flight."
Consider buying offsets for any trips you have planned on Native Energy or Cool Effect, and next time you book, do it with an airline that offers carbon credits with each ticket. Major flyers like Jet Blue, American Airlines, and Delta do!