Advice:
1. Keep your options open, as others have said.
2. Do your homework and factor the price of a PPI into buying the final contender.
3. Price shop using one of the online vehicle buying sites, IMHO cars.com is the best as it is intuitive to navigate and you can tailor the search so well.
4. In searching, get to know your market. Mileage, options, model year, things like exterior/interior colors can also fetch premiums.
5. Research the dealership(s), IME (will not go into any detail) the poor online ratings are typically the most accurate representation of a dealership. Many slimeballmen, I mean salesmen, will offer some sort of discount for a good online rating. Tragic, but it happens all the time.
6. I suggest test driving at dealerships other than the dealership the car you want is at, and when you walk into them, tell them that all you want to do is test drive the car, and that you are not interested to buy.
7. When you find a vehicle that you like to drive and it`s not the one you want to buy, find the one you want to buy.
8. Before you even think about going to the dealership to get the *one*, know how you will accuire the vehicle, that being cash or financing. If you are financing, talk to your bank to see how much you are approved for and set a max price for yourself. Have all of your side of the paperwork complete before physically going to purchase the *one*.
9. If you happen to purchase the vehicle on a Thursday, Friday, or Saturday, (and it passes the PPI) it is in your best interest for your own sanity, to give the dealership at least four days to get the vehicle ready. A good dealership is busy and you will get frustrated having to wait all day and the salesman will get frustrated too. Giving them time works in your favor.
10. In and Out, the less time you spend in the salesmens face and viceversa, the more you two will like each other. You hate spending an entire day at the dealership and he will hate spending the entire day with you, no matter how nice he is.
11. Of course ask the salesmen how much the dealership has in the vehicle and what they`ve done to it, this will give you an idea of how much room they have to budge on a vehicle.
12. REMEMBER, IT IS A USED VEHICLE. Manufactures send brand new imperfect vehicles out their doors all the time; don`t ever expect a used vehicle to be a gem because it`s been used.