Using ITA Matrix is pretty easy.
Using ITA Matrix to actually find better deals takes a lot of knowledge about how the airline systems work.
If you're only looking at flights out of a particular airport and with a specific (default) routing, you'll probably not find anything better.
If you know that certain airports are hubs, or that a particular carrier has a slightly longer route that takes you via a certain city and maybe have a longer layover then you might be able to find some really good deals.
Being in Australia, I really don't get to take advantage of these things at all.
If you're only looking at flights out of a particular airport and with a specific (default) routing, you'll probably not find anything better.
If you know that certain airports are hubs, or that a particular carrier has a slightly longer route that takes you via a certain city and maybe have a longer layover then you might be able to find some really good deals.
Being in Australia, I really don't get to take advantage of these things at all.