I've used cheaptickets dot com and expedia dot com, both were about the same.

I know Shrag uses Kayak since it lets you compare the different sites and pick your preferences, I don't know what I can suggest in the way of tips, it's mostly like buying anything online, you put in your destination and departure, dates, and click search. They'll email you reminders and boarding passes and all.

I have often used expedia.com to find the cheapest flight to get from A to B, but I can recommend Google Flight as a way of double checking, to ensure that you're getting the best deal.

I'm not sure what discount airlines serve Canada, but in the You Ninety States several of your discount airlines don't show up on any website but their own. Southwest is like that. If one is going to fly them, one has to check one of the aggregate sites- Kayak, Hotwire, Orbitz- and then check the discount airline individually to see how it compares.

Expedia.ca is a good way of comparing fares offered by multiple airlines all in one place, but before you book with them, check on the operating airline's own website to see if the cost is the same. Once in a while, the airline will sell the flight to you directly for less than what a third party will.