Here is a hint...that doesn't mean you have to drive hard bargains.
For some reason there is this idea that when you buy a home you need to negotiate a price less than the seller is offering it for sale. Once negotiations are complete with the seller, the aim to "get the best deal" is now focused on everyone involved in the process. Asking realtors to reduce their commission, lenders to pay or remove fees, inspectors, appraisers, all being asked to reduce their income.
That's not advocacy. It does not work.
Here is what advocating for oneself looks like. I know how much I make and I have my own budget. I know my budget is based on tested and true cash flow management principles. Even if I am approved for more I will not spend more. I will be in a position to move forward before I even begin. I will hire professionals based on trust.
Now go be your best advocate!