I view this a little differently as I am not at all fond of the back and forth haggling to "settle". I go into discussions with a price in mind, a solid and realistic one, and I won't deviate as long as I've done my homework and know my number is reasonable. There is always another car when you are buying new. The one you're looking at is not the only one in existence - if it is, it's not the kind of car you can really negotiate on anyways.
For many vehicles there are forums (reddit, edmunds, regular old google-them forums) specific to that manufacturer and/or vehicle. In most there will be a section for prices paid for vehicles indicating exact model and trim level, OTD price paid, location, and financing info. Once I have narrowed my search to a particular vehicle, that is the route I take to figure out exactly what I am willing to pay.
Once you know exactly what you want and what you're willing to pay, I'd start by contacting the dealerships within a hundred miles or so and asking them for quotes on the desired vehicle. You can always expand your range if needed. See what they come back with. If none are in the range you want, go back and counter and see what response you get. You need to know exactly what you want and are willing to pay for (trim level, add-on's - NO!, etc.) when you are doing this. I would do every single part of this remotely if possible, and only go in to test drive the vehicle and sign the final paperwork once the price is agreed on.
Personally I've always pursued my own financing beforehand, but I'm also willing to let the dealership match or best what I have if they are able since that is another place where I think they may benefit from incentives. The market for new (and omg used...don't even get me started) cars these days is different than days of old, but it's also possible to have a really good handle on what a current fair price would be. I'm never aiming to squeeze every last penny out of the deal at the expense of time, but I want to know I paid a fair price when I'm done.
