Transportation
Aleksandra Radic
Skyscanner
This is one of the best websites for looking for cheap flights. We usually check the price here and then compare it directly with the Airline's website.
Momondo
Another excellent search engine for finding the cheapest flights!
Google flights
We used this more in the beginning to figure out the best and cheapest flight from one city to another. It has a world map and prices scattered all over so you can basically see the cheapest flight available on a specific day. The only bad thing is that you can't book flights through here.
Rome2Rio
Great for figuring out how to get anywhere. You can enter any destination and it will instantly display flight, train, bus, ferry and driving options with estimated travel times and fares.
Decolar
This is a good website for travelling in South America. We've used this in Brazil so far. It's good for flights, accommodation, etc. The site is entirely in Portuguese so make sure you right click and use google translate to English.
Try using any of the above mentioned websites (apps available) for narrowing it down. We found it cheaper to book directly with the airline companies on most occasions.
In Europe, we used Ryanair, Easyjet, Wizzair, Pegasus Airlines.
In Asia, we mainly used Air Asia, JetStar and sometimes Tiger Air.
In South America so far, we've used Tam Airlines, GOL Airlines, Azul.
Our favourite airline so far has been Etihad! If you ever have a chance to fly with them, do it! Everything about it is amazing including the food. We felt like we were on spaceship!
Uber
Gotta love Uber. We've used it anywhere it's available and it's pretty much always cheaper than a taxi. Loved using it in Bali. Every ride cost us $1-5.
Grabcar
Basically like UberX in Asia.
Greyhound Australia
We travelled mainly by bus and the Greyhound was awesome. It was really comfortable, with wifi, air conditioning. If you book online they typically offer discounts.
Opal Travel App
This was a very useful for getting around in New South Wales. It has bus, ferry and train information. It gives you a fare estimate as well.