Here, as in the UK, most property is sold by local agents.
Look around your area and talk to friends with the aim of identifying three or four good local agents. Invite them to see your property and value it for sale within one, three, or six months. Discuss how they will market it and what commission is payable.
Make sure you have the escritura (deeds), local rates (IBI), electricity, and water bills on hand. Don’t show the escritura until after you have obtained a valuation.
Many agents in Spain have the habit of asking the owner how much he or she wants. Say nothing. Ask them to give you a valuation and they will.
Choose your selling price and appoint your agents. Granting exclusivity is probably not a good idea. Needless to say, don’t sign anything you don’t understand.
Of course, there are alternative routes for selling without an agent but they are less likely to succeed.
As you may have guessed, I am an estate agent.
Good luck! 😉