The best time to visit Cancun is December to April during the peak season. Even though the crowds are heavier, you'll experience near-perfect weather and find some of the cheapest flight and room rates for a winter getaway at the beach.
Advance booking is the best way to get cheap flight to Cancun. Book 6 to 8 week in advance to grab cheap flights. Airlines such as Aeromexico, Jetblue, US Airway and United Airlines offers great discounts on airline tickets. From the airport to city take taxi.