In reply to Mattyk:
A couple of tips.
Get a range of valuaions from agents who sell similar property to your own
Don't be emotional. This is no longer your home, it is an asset waiting to be realised.
Do not try and talk an agent up to your perceived valuation. If they don't believe it how will they be able to convince a potential buyer?
Ask them their database of propective buyers
Which websites do they use? Rightmove is by far the largest although some specialist properties will do better on other sites.
De-clutter and remove personal effects. Allow buyes to imagine themselves living in their home - not your home.
If an agent values a property to highly it is because he wants your business but does not have a buyer
If an agent values your house too low it is becuase they have a buyer ready and can turn the property with minimum effort and marketing expense.
Who will do the viewings? Most agents send a seasoned professional to do valuations and 17 year old to do the viewings.
I put my agents on a sliding commission scale. If they get what they value it for they earn their fee. Anything less and the commission rate drop. Over achievement is highly geared as well.
Don't even bother listening to offer from buyers who cannot proceed yet. They're not in a position to do anything.
Good luck!