The dealership can give up front end profit (selling price of the vehicle) and hold rate (increasing the rate on the lease) creating back end profit or vice versa. All you really need is two or three dealerships that have a comparible or identical vehicle and get quotes. That little bit of leverage is usually what you need to get to the bottom line.

If you are asking about residuals and money factors they will understand that YOU understand leasing, which can help. I haven't had a lot of customers over the years that asked about money factors. Several have asked me about residuals. It was usually quickly apparent who had had experience leasing vehicles.

If you can build a lease calculator in Excel with my formula in the OP or find an app that will calculate it and then ask the dealership for all the info to do the calculation it will go a long way in helping you understand how to find a good lease.