1. Some tickets give you more flexibility than others
When booking your flight, be sure to READ THE FINE PRINT. Some tickets offer the freedom to change the dates or location of your ticket and some don't. The tickets that offer this freedom are typically more expensive, but I tend to lean towards them just to have a safety net. What if you're late? What if the person/group you're planning to go with flakes on you? You might be okay taking that risk, and that's fine, but know before you book your ticket what you're getting into.
2. Best day to buy is Tuesday
Airlines typically announce deals on Monday night, which means Tuesday is the day to buy!
3. "Cheap" Airlines have extra charges and more issues
Cheap flights are enticing. Traveling internationally for $99? Going to Florida for $60? It all sounds great, but these airlines cost
less for a reason. They'll charge extra for checking a bag, extra for food/drinks on the plane, and extra for anything else they can. Some of the flights I booked on "cheaper" airlines ended up being the same price as more expensive airlines when all the charges and fees were through. Not to mention that some of these airlines have pretty bad customer service - hanging up on customers and all other sorts of disasters. Do your research before choosing an airline.
4. Pack light
Because some airlines charge for checked bags, try to keep it down to one carry on and one personal item (purse, backpack, etc). Not checking bags also avoids the issue of airlines losing (or delaying) your checked luggage.
5. Book in advance
Flights get more expensive as you approach your flight date so book in advance! Plan your trip at least a few months prior to avoid spending a few extra hundred dollars.