Are these deals for real on scoot airlines? https://www.flyscoot.com/en/promotions/real-deal-india?utm_source=in-email&utm_medium=email&utm_campaign=PR
You should check out kayak they are one of the best when it comes to cheapest airfare. They also recommend whether a round trip to your destination is cheaper or if trips to and from your destination are better. Worked well with me when I travelled south east Asia this summer :)
As mentioned by Sreshti, skyscanner is a good way to find cheap flights. Also look out for Air Asia deals - sometimes you get amazing discounts (but look out for restrictions on cancellations and baggage allowance)
The cheapest way to fly from India to Australia is usually via budget airlines with layovers in Southeast Asia like AirAsia (via Kuala Lumpur) or Scoot (via Singapore). Booking early and being flexible with dates helps save more.