I'll just die if I put this in the wrong forum! Needed suggestions from someone who know the inner workings on auto sales.
Operate on the assumption that they are all scumbags.
Before you walk into another dealership, do all your homework. Ensure you already know the car you want and the price you are willing to pay. Ensure you know the trim and all the options you want and don't let the saleman talk you into anything different.
Forget about a trade-in. It only gives the salespeople the opportunity to confuse you and increase the price while making you think you are getting a good deal. You are better off selling the car on your own. If you must trade, then have the car detailed (spend at least $250 on this) and demand at least blue book value or you will walk out the door.
Forget about doing your financing through the dealership. NEVER, EVER finance through a dealership. Get a car loan from a bank or credit union and bring the bank check to the closing. If the business manager tries to add on additional charges (and they will), threaten to take your bank check and walk out the door.
Forget about any of those extended warranties they try to sell you. It is a rip-off. Factory warranties are sufficient. Find a good garage to do your routine maintenance. Only have your car serviced by dealership if you are having warranty work done.
Don't let dealership get away with sticking "prep cost" or "cleaning cost" onto the deal. You are buying the car new - why would they need to clean it? Besides, they are paid by the manufacturer to prep a car for sale. If you pay them then they are getting paid twice for the same thing.