We would look 3 recent sold comps in the neighborhood, 3 active listings, and take in to consideration relevant updates to the home, attempting paint an accurate picture for you what the fair market value of the home is. Of course, many purchase and sale contracts offer the opportunity for an appraisal contingency. This aids to make sure that a buyer doesn't pay more than the house is worth.
I hope this helps.
As always, you can message me directly and I would also be glad to discuss.