Verified answer

If you go to this website:

http://www.low-cost-airline-guide.com/ or

http://www.skyscanner.net/

you can pick the European city that you want to fly out of and the one that you want to fly to. Then, they show you what airlines fly that route and they give you the link to their website.

Google for cheap flights Europe and see what comes up.

After you have found a few flights, go to the sites of those airlines, and see what they cost if you book direct.

Then consider if booking at several sites is worth the savings.

And check which airport the lines use, as some cheap ones use the airports far out.

(Ryan Air is no use if you want to travel London-Amsterdam, and there are more like that.)

Visit http://iluvtotravel.blogspot.com/ for travel tips and also to book plane tickets, hotels, car rental, train tickets, travel insurance and more and also what to do and where to go when you arrive at your destination, from the author's personal experience in travelling.

try ryanair.com