Try going to a website like airfarewatchdog and input your approximate dates. They will inform you periodically what the current airfare is, whether it is a good rate or not and whether they think it may go lower. I'm doing this for a winter trip and so far the emails state that they are expected to go lower.
I read something recently that stated airfares tend to be their lowest about 2 months out and the best day to book is Thursday.
Also look into airline credit cards offering free companion fares. I pay $195/year for my Delta Platinum card but it gets me a free companion ticket plus free checked bags and early boarding. I only use the coupon on an expensive, long distance flights.