I am able to take 4 trips to Europe a year while using miles and cheap, cheap fares.

One strategy is to check Virgin Atlantic to London on a daily basis. I have had very good luck with getting fares of between $300-$370 spring and fall by doing this. Once I also got a fare of $300 in July, but that was a few years ago.

On the miles front, I am now using a Starwood American Express card since the points accumulated can be transferred to just about every airline FF program. Then, I charge everything I can possibly charge, (including my father's funeral, but that's another story) to get 'free seats'. In quotes because there is a fee for the credit card, and tax to pay on the ticket. And, I also travel for business, although not so much as I used to, and accumulate those miles courtesy of my company. If you don't travel a lot and are thus not accumulating real miles, the credit cards like Bank One could be good since they require fewer miles for a trip, but you can't add real miles traveled to your account.

Is it an obsession for me? You bet it is. I need to have those trips dangling in front of me for something to look forward to. It's also a game to see how many ways I can get my trips. I must say, it's getting more difficult to get the free trips, but still somewhat doable. There is also the 'book 331 days ahead of your trip' to get the seats. Even that is harder. I am now trying to get a ticket for the Caribbean on American for next January. I booked at 2am, 331 days out to get the outbound flight, but am having difficulty getting the return as the free seats aren't posted yet. That's a work in progress.

I hope this helps to get you started.