Tickets for the 2015 season will go on sale at some point in November. Tickets you buy during this period of mid-November to approx February will be your best deal: the price is the cheapest it will be all season, plus you get the Bring a Friend (BAF) tickets. It think it's usually 5, and they each have a set of dates through the year when they are good (if I remember correctly, July and November are blacked out since they are the busiest times, as well as some of their other busy weekends).
The later you buy the tickets in the spring the price will go up a little bit, and there will be fewer dates available for the free BAF passes to be used.
Some years they will do an offer during the Christmas festival that allows you to turn a one day pass for 2014 into a season pass for 2015 (but you don't receive the BAF passes for next year).
BTW, welcome to our forums! Hope we were able to help, and feel free to ask as many questions as you need!