Look at their local sales record first

Anyone can talk a good game about knowing the market. What you want is evidence. Ask each agent you're considering for a list of properties they have actually sold — not just listed — in your postcode over the past twelve months, ideally similar in type, size and price bracket to yours.

Look closely at the difference between the asking price and the eventual sale price, and ask how long those homes took to go under offer. An agent with a long list of instructions but few completions may be winning business by overvaluing properties, then quietly asking sellers to reduce a few weeks later. Ask how many of their sales completed rather than fell through, because a high fall-through rate is a warning sign worth taking seriously.

If you're selling a flat, a period terrace or a new-build, check that they have specific experience with that kind of property. Local knowledge matters most when it comes to quirky layouts, leasehold complications or a street that buyers either love or overlook.

Compare fees properly, not just the headline percentage

Commission is the easiest thing to compare and the easiest thing to misunderstand. A quote of 1% plus VAT is actually 1.2%, and on a £300,000 sale that's £3,600 rather than £3,000. Always ask for the total figure in pounds, including VAT, based on your expected sale price.

Then dig into the small print:

• Sole agency or multi-agency. Sole agency is usually cheaper, but it ties you to one agent for an agreed period. Multi-agency costs more but gives you more than one route to market.
• Contract length and notice. Anything beyond twelve to sixteen weeks deserves scrutiny. Ask exactly how much notice you must give to leave if you're unhappy.
• No sale, no fee terms. Check what happens if you withdraw the property, and whether photography, floorplans, Energy Performance Certificate costs or portal fees are deducted from your final bill.
• Additional charges. Some agents charge extra for accompanied viewings, premium portal listings or a for sale board.

Ask exactly how they will market your home

A good agent should be able to talk you through their plan without reaching for a brochure. Ask which property portals your listing will appear on, and confirm it will be on the major national ones as standard rather than as an expensive upgrade.

Find out who pays for professional photography, a floorplan and a virtual tour — these make a measurable difference to how many people click and enquire. Ask how they write their descriptions, whether they use social media or local advertising, and whether viewings are accompanied by someone who actually knows the property.

Practical details matter too: will they hold evening and weekend viewings for buyers who work office hours? How do they qualify people before they arrive, so you're not tidying up for time-wasters? If possible, look at a live listing of a similar home they're currently marketing and judge the quality for yourself.

Test their communication before you commit

The way an agent handles your first enquiry tells you a lot about how they'll handle your sale. Note how quickly they respond, whether they answer your questions directly, and whether they follow up when they say they will.

Ask who will be your main point of contact day to day — the person sitting in front of you, or a central team you've never met. Get a named contact and agree how often you'll receive updates, whether that's weekly or after every viewing. Read online reviews, but focus on the specifics: comments about chasing solicitors, honest feedback after viewings and clear communication are worth more than a generic five stars.

Trust the agent who gives you a realistic valuation

The highest valuation is rarely the best one. An inflated asking price attracts fewer viewings, sits on the market, and usually ends in a reduction that makes buyers wonder what's wrong with the property.

A trustworthy agent will justify their figure with evidence: recent sold prices for comparable homes, current competition on the market and an honest view of your property's quirks. They should be able to explain their marketing plan clearly, tell you how long they expect the sale to take, and be upfront about the price you're likely to achieve rather than the one you'd like to hear. If someone quotes comfortably more than everyone else without a convincing reason, treat it as a sales tactic rather than good news.

Questions worth asking before you sign

• How many similar properties have you sold in my postcode in the last year?
• What is your total fee, including VAT, in pounds?
• How long am I tied in for, and what notice do I need to give?
• Who will handle my sale, and how often will I hear from them?
• What is included in your marketing, and what costs extra?
• What sold price do you realistically expect, and why?

Take your time, compare at least three agents, and choose the one who answers these questions plainly. A good estate agent is not the cheapest or the loudest — it's the one who can explain exactly what they'll do, back it up with local evidence, and keep you informed from the first viewing through to completion.