The old adage 'first impressions count' is particularly apt when showing your house. The vendor is likely to make up their mind within minutes, if not seconds, of seeing the property so you must ensure that it is in the best shape possible. You want to draw a positive reaction from every room, even a cupboard "mmm what a handy space"
You don't have to spend thousands on a complete makeover but whatever the property age, type or location, home buyers are attracted to clean, spacious and reasonably well looked after houses.
Try and sort all those little jobs that you've been meaning to do; cut the lawn, fix the squeaky steps, broken tiles etc. Unless you're selling a real fixer-upper, it is unlikely the buyer will look forward to doing them.
Space is important too. Most of us live in an ebb and flow of tidiness with some days being better than others. However a quick tidy up really helps. Simply removing the clutter from counter tops, tables and rooms can make a huge difference. Make the viewer think that they'd like to live in such a clean and tidy space. Sell the dream rather than the reality.
When you have done the Mary Poppins bit, get a friend or neighbour to review the house like a buyer would. Get their opinion on how it "shows."