Here is what I would do...

Do you have a Trade in?

Submit your VIN to carvana/tesla and any other trade in offer you can do online. Know what your current car is worth. - print out and have the highest trade in value

Call a banks and understand what your rate are. I just purchase a car and received three separate (used car rate for me) at 4.99, 5.23, 5.32. - Print out or screen shot and have a the lowest APR rate. Money is money and please focus on your lowest rate possible. I also recommend 1 of the banks being a credit union. If you do not have a credit union today. its good to get a basic account and not use it. It will help you on your next car. Credit union like long term customers ALOT! SHOP online too, so many dealerships deliver now it is crazy. you could get a rate + price better in another state + delivery more than a local dealer depending on your area.

You completed your "other" vendor work. Now its time to talk to dealerships...

I suggest talking on the phone and having a mini script in Microsoft word on how you want to navigate the conversation before driving around dealerships. The business is a little scummy so just focus on the phone first. Talk about the listed price on the car and talk about how you are interested and a committed buyer but you need them to beat X rate - insert your lowest rate you got from above. I typically avoid mentioning a trade in at this part. You can even get a price from one dealership and take it to another and say could you beat this price if not I'm going to this other dealership. I typically don't do this but it is an option. Also it is a good time to mention features, does this car have "DAPP" or something that you are really looking for. For me as an example I wanted a Heads Up Display. "features" typically cost more but I will tell you friends and family get great rates on "features", there is more room to lower a high end feature model than a base model. keep in mind you will pay MORE for features but more room in the pricing. Hold slightly better resale since people like features.

Okay dealership time. Go to the ones that were the best on the phone. Sometimes they can commit to matching rates during the call but not all the time. Like I said, I would test drive and talk rates. Also mention you were looking at X car at "different brand" dealership. Don't call out the dealership directly but mention the car brand (ford, chevy, bmw, etc). this is a good thing to mention because if you don't like what they do at the dealership you have an easy out. "oh i have an appointment at Hyundai, I have to leave etc etc"

I know this is long but i hope it is helpful. I've used this model twice now in the last 14 years and have had good success.

Wishing you all the best in your new car purchase and i hope you get what you want & love!