You, on the other hand, need to remain steadfastly focused on the right price for the car – not the financing, the value of your trade-in, or anything else. When they try to talk about the trade-in, you say that you need to talk about the price first. When they try to talk about financing, tell them you already have a preapproved offer so you can take that topic out of the conversation.
Some dealerships have gone to the model of no-haggle pricing, with fixed prices on all of the vehicles they sell. If their fixed price is in the range that you are willing to pay, that’s great, but understand that they are likely to try to get more profit out of the deal by selling you expensive financing, costly add-ons, or lowballing your trade-in value.