a new car

I read a book "The Insider's Guide on Buying a New or User Car" by Burke Leon & Stephanie Leon. The author Burke is a engineer scientist type of guy who got out of job thus started to take it seriously buying a new car. The book's fairly readable and seems to offer good advice. However, after I bought my car, I realized the dynamics of negotiation could not be captured by simple rules; you have to practice it in reality to be a better negotiator. Some notes to share:

Part I.
Your trade-in:
- a good price through a dealership would be wholesale minus $300.
- tell the saleperson it's very important you get a very best price for your trade-in and after that the rest of the sale will go easily; tell them you need a good price for trade-in also to afford a down payment. Later, when moving on to the new car, tell the salesperson the only important thing to you is a good price on the new car. The salesperson is trapped and does not want to risk losing the sale at this point.

Going to the showroom - what and whom to bring
- a distractor - someone who can interrupt the salesperson's practiced presentation and take them off guard.
- a yellow pad, two types of pens: verbal agreement is less effective as written ones; ask sp to confirm and prevents him to confuse you.
- results of homework: the prices worked out prior to the showroom.
- a calculator
- interest and payment tables: verify the monthly payment.
- payment and financing verification from your lender: done before going to the dealer.
- Proof of insurance.
- A clean car: remove everything except essential documents in the glove compartment.
- All the keys to the car.
- The title of your trade-in (?): not a salvage title.
- Service records.
- Wear comfortable, presentable clothes.
- Attitude: treat me right or I am out of here; I will not be messed with. Don't be emotional, be a little unpredictable and cool. Not to gush about the car. Be neutral.
- Keep a certain distance to the sp and don't let him believe you like him.

Total image:
- dress well, look prosperous.
- come with trade-in clean, empty and read to be traded.
- say "I want to buy a car today" several times.
- play a bit dumb at the beginning a seize control later.
- Say "this deal is just not good enougn" but don't tell him why.
- when you are near an agreement, say "No" just one more time and see whether something else might happen.