As long as you remember to NEVER fall in love with a car you're looking at and are ready to walk on a deal you don't like, you'll be fine.
Never used it but like CarMax for buying a used car. I never thought buying a new car and getting a good deal was all that difficult. Easy to find the invoice for the car. kbb.com, nada.com, Edmunds.com & etc will show you the invoice cost of the vehicle. You determine how much you're willing to spend based on the invoice and taking rebates into account. The vehicle I just purchased I bought at invoice less two $1000 rebates and would have had another $1000 rebate but chose 0% financing instead. Another dealer was offering a minimum trade in of $5000 and our trade was worth $2500 due to unrepaired accident damage. That $5000 also came off the price when they matched the deal. I would not have pulled that off on my first new car, but easy at this point in my life.
When it is your first deal it's not difficult to buy a car for $300 over invoice. Just have to be firm and willing to go down the street if they won't work with you.