There is no specific way to get low cost flight tickets. You will need to keep checking the discounts being offered by several sites like cleartrip or makemytrip.
One more good source of getting good discounts on air fare is iXigo travel app which is available for Android on Play store. You may also use the Ixigo website for the purpose of getting discounted airfare.
Apart from the above options, some price comparison sites can also be helpful in getting the list of low cost airways and discounted offers. Expedia is one of the best sites for getting some special offers on airfare.