I always express tons of interest, test drive, then sit down to talk numbers. Always talking about much I want "that vehicle" Then I will ask for a huge discount on the sticker price seemingly out of nowhere, which they will deny on the spot cause they're manager would never "allow me to give it to you for that price". Then I walk out. I usually do this at multiple dealerships, and await callbacks. On the last vehicle I purchased I got about 4k off plus extra stuff not normally included in the trim level we bought, and the one before that, 3k off. Timing helps (end of year/month), but most dealerships want sales.
Also never pay for doc fees, unless they are giving you a break elsewhere. Total bullshit.