COMPS COMPS COMPS.
Find out when Greg and Robin will next teach COMPS at their saturday morning meetings. It's the best, shortest and least expensive workshop I've attended on the question.
It all comes down to the most recent sales of comparable properties around the neighborhood. A.K.A. "COMPS". Whatever a house sold for a year ago is too long ago. whatever sold five miles away 'may' be relevant but a house with the same layout on the same block is better. REALTORS - agents and brokers - have the best resource generally available, the Multiple Listings Service or MLS.There's also a pretty good subscription service for non-REALTORS covering Tarrant County called Investway.com. It'll cost you some, don't get me wrong, but if you don't have access to the MLS or a REALTOR who will give you the comps you need fast, it's worth the money. Hope that starts to answer your question.