Begin by consulting a travel guide that you trust. All guide books have price and quality ratings, and in my experience I've found them to be quite reliable. I've had a few disappointments, but I chalk it all up to the adventure of experiencing the unknown. You'll have better luck finding cheap sleeps if you're willing to take a cab or train into town. Once you've found the place you'd like to stay don't use the phone to make the reservations, but use the hotel's fax machine instead.
Fax machines are ideal for a variety of reasons.
You can make clear in writing exactly when you want the room, how many people will be staying, whether you require a private bath, etc. A fax takes mere seconds to transmit, can be sent without regard to time differences, and costs only pennies in long-distance tolls. All of this time, of course, the long-distance meter is clicking away. When you fax your reservation request be sure to ask for a confirmation to be faxed back to you. This is very important.