Credit Card
I probably started playing this game a little late, but better late than never! This is more of a long term strategy of finding low air fare to Europe.
To get to Greece or Europe you need between 50,000-80,000 miles(dollars) depending on the card. When you first start it seems like an insurmountable challenge! I thought so until I saw the little miles slowly adding up on my monthly statement. If you use it for your personal expenses(you can pay a lot of bills by credit card) and your business expenses(if you own a business) then the miles can add up pretty quickly!
There is usually some limit to the amount of miles you can accumulate in a month and mine was 7,000, but that didn't prove to be two much of a problem as I very rarely charged that much on my credit card in any given month. If you do charge that much then you can always look at getting a second credit card(or a third!).
There are actually two kinds of credit cards with miles. One is independent where you accumulate the miles/dollars and then contact the credit card company to book your air travel and have a choice of airlines to fly. The other is associated with a single airline and your dollar/miles are automatically added to your Frequent Flyer account for that given airline. Both seem to work pretty well, but there are a couple of things you need to watch out for; yearly fees(usually around $79) and high interest rates.
There is usually some kind of caveat at the back end of the purchase(some kind of service fee or you will only be able to put so much towards the ticket(I think that 60,000 mile/dollars equaled $800 so I would have to pay anything over $800. All these little things add to the price of your "discounted air fare" so you need to be careful. If you take 6 years to get enough miles and have to pay $79 a year that's $474 you've spend on your "free ticket" and with a couple of other charges you may see all your savings eaten up!
I signed up for a USAirways credit card for $79 and received FF 25,000 miles, plus another 1 miles for every dollar I spent. That gave my USAirways a large boost! I'm not sure if I'm going to renew the card as $79 sounds a bit high, plus I just received an offer for 35,000 USAirways miles with another credit card.
Between my two credit cards I usually get a free ticket every two years or so.... that's not bad, if you're traveling with one or two other people then you have a 33-50% savings if you have to buy one less ticket!
So don't discount the power of using a credit card that gives you miles!