Hiya!
Thought i'd lend you my Airline Knowledge for this post..
Airline sales are based around Seasons
The Peak Seasons are: 1st July - 29th Sept. & 1st Dec - 31st Jan
The Shoulder Season is : 1st May - 30th June & 1st Feb - 30th April ( depnding on when Easter is)
Low Season: There is no low season really! lol Oct & November is a pretty good time to go though. ( oh apart from Half Term week at the end of Oct!)
With regards to booking tickets.. the earlier the better! There's a big misunderstanding that if you wait till the last minute you can get cheap tickets as the Airlines want to get rid of them. That is a complete lie. The airlines will charge you more for last minute bookings, as there are more admin fees to cover.
Also where possible always ask for a E-Ticket. It can save you around £20 per ticket in printing costs! Plus the bonus is you can never lose it!
At the moment Singapore Airlines and Malaysia Airlines are in direct competion with each other. Singapore have just ordered 2 new Airbus 380's ( the new double decker!) So they are able to cut their prices dramatically.. Malaysia have lost Business becauase of this and so it's now started up a price war.
Bonus with Singapore Airlines is that they are part of the Star Allience. This means that if you join Their Frequent Traveller Program then you can use you're points not only on Singapore Airlines, but on United, Air NewZealand , Air Canada, BMI, Lufthansa, Thai, Tap Air Portugal etc..
Which is a good deal!
Oh and lastly check out Emirates..... They have tickets for around £600 if you leave before the end of June and they are fully changable! Bargin!
Hope this helps..