I find even if you want something, you have to go in with the attitude that you don't.
If the salesman knows your drooling over a certain machine, he also knows you will do just about anything to make sure it becomes yours, including paying too much.
When I went shopping for my X740 in February, I knew 100% I wanted it, but I didn't act like it. I went into the dealership with the attitude of "if this works out, great. If not, I will find another deal elsewhere" I had no intentions of signing the papers that day. I managed to land a great deal with a lot of freebies thrown in, and I do believe that was partly because I didn't care whether it went well or not, and I honestly didn't.
You do have to be careful though. Some salesman definitely have their nose in the air, or don't care about small value sales. Some salesman will sense that you don't care, or your acting like you don't care, and they will simply say no to any demands you make. If the salesman does not care to make the sale, pretty much anything you do will not help you, unfortunately, he is the one who sets what you will ultimately pay. If you sense the salesman does not care about you, the sale, or sales that don't carry price tags over $100,000, I would find a different salesman. If you can't find one where your at, move on to the next dealership, your bound to find a good one sooner or later.