First thing I do is research what hotels are in the area. Write down the one's you wouldn't mind staying at. Note the star rating on the hotel. Is it a 3 star, 4 star hotel. This is one factor used in the bidding process. Also note the average cost per night. Go to the hotels website if they have one. This will give you an average basis to bid on.
Also, note all these factors for the hotels you don't want to stay at. Once you place a bid and if it gets accepted, that's the hotel you will get. Roach motels will usually have less than 3 stars. Bidding on 3 stars on up is usually the best bet not to land up in a roach motel.
After you gather your information, then start your bidding process. For example: Let's say you saw a 4 star hotel that charges $200/night. You can offer $150/night and see if someone accepts it. If not, they ask you to change your bidding. Once you reach the level you don't want to bid on anymore, than I would stop there; if you don't get an offer by then that is.
I don't know what type of cancellation policy priceline has. You may want to look into it before bidding. Just in case you think you're not going to like where you're staying. I've usually been pretty satisfied with the results. Depending on where I'm going, I can usually get a 4 star that charges $125/night for $85/night. If not, then I stop bidding. Just all depends. I've noticed that most places won't go more than 50% off. They will usually go around 25-30% off their base price.
Hope this helps.
