When is the cheapest time to fly to the USA from Australia?

I think the best time to travel would be a night flight since most people travel during the morning and afternoons[which means ticket prices are higher] the best season would be spring because a lot of people travel during winter and summer. I guess autumn is an ok-ish time to go also, but I say spring at night time. I dont really know any good websites with sales. I dont even trust them. : / I usually just buy my ticket months in advanced and you turn up with a pretty good bargin. Hope this helped and if you decide to go, have funS :]