There are two different methods of attacking this and the one you choose depends on your goal.
Some people above are speaking in utilizations percentages in the advice they are giving you. I would imagine that with the situation you're currently in, you aren't planning on applying for new credit any time soon. That said, utilization percentages are essentially irrelevant as are your scores (these two factors are directly related of course). If you goal is to financially get things under control, you'll want to pay the least amount of interest possible which means tackling the balance of the highest interest rate card(s) first.
If you have no intentions of applying for credit in the relative near future (until you get yourself out of this mess) then my suggestion is to not worry about utilization percentages and thresholds.
