Have you checked out the Dave Ramsey baby steps? I disagree with his politics but he's good at helping people get out of debt. He recommends the snowball method (which, while mathematically not the absolute fastest way to pay off cards, gives more immediate reinforcement -which helps people stick to it - and can lower required payments faster).
The idea is simple - put any extra on the card with the smallest balance. Once that's paid off, add what you were paying on that to the card with the next smallest balance and so on.
