Which route keep my fare low? I never took this route.

There is no direct flight. I am open to break some places in Europe, Malaysia, Kerala or Toronto.

I appreciate some tips here - is it better to get round the world trip, cheaper? Tips on airports and airports to avoid?

Than Google flights, following the link from Bing search took me to Qatar and gave me lowest fares at $777! They seems partners with BA. But BA did not give that fare.

Should I use a travel agent? Who would that be? Outside US, people are using travel agents.
What might be the best tool to find fares for multi-city trips?

I do like to go to additional cities like Kerala, Malaysia. I could do Toronto, Norway later.