Have a look at which estate agents are active in your area and with your house type. Probably more important in rural areas.
Have a look at their ads online, and how professional their photos are. For example I'm aware of 1 rural based agent that takes their photos with a mobile phone!
Then invite 2 or 3 agents you've chosen around to have a look with a view to selling for you. Ask for their advice on how to present house better, and who they would be marketing it to. You'll get 'a feel' for one of the agents. In my own case I met one who was really nice, but not a seller. I'd love to buy a house from her, but there was no way I'd let her handle a sale.
Then ask about costs. The recognised brands tend to be a bit more expensive, but depending on your house type they might be a better fit. As with everything in life, haggle! Fees are negotiable.
Ask them all for a valuation, and what they'd like to put it on market for. The mid point between all will be closest to reality. Some will value it higher to try get the business, but that doesn't mean they can get that price.