High season runs from Mid December-April.Here is a helpful guide to when to book tickets.

http://www.frommers.com/destinations...093020006.html

Shop around, don't just assume the airline websites will offer the best rates, often they have the worst possible rates.

Hotwire/Priceline and even hotels.com have better rates "usually" than Orbitz or any other "deal" sites.

I strongly recommend avoiding groupon/deal of the day sites when looking for airfare/hotels, they tend to have more hidden fees and blackout dates.