How much should offer when negotiating used car price?

How much should offer when negotiating used car price?
Depends on your style of negotiation, the car itself and how much you want to end up paying for it.

If the liabilities seem high, offer a really low price.
If the seller is desperate, stick to a low price.
If your at a good dealership, negotiate the price around anywhere from 5-25 percent lower then you would a new car dealer(depending on how well you can haggle the guy)

I think for every 14 thousand dollars your going to spend you should get 2-4 thousand off.(4 could be greedy and hard)

Get services included, its a used car.