i am in the process of both buying my next place and selling my current flat. we did everything possible to 'stage' our flat so that no matter who walked through the door, they could immediately see the purpose of each room (as parkesquay says - if it's a bedroom - put a bed in it). the flat was clean and tidy throughout as well. we received an asking price offer on it within 50 minutes of it going on the market - so staging really does work. amazingly another flat in my complex is also on the market and is being marketed as a 1 or 2 bed-roomed property (they'd turned the second bedroom into a dining room) - funnily enough, this one's still on the market!
as a buyer (i do have the ability to look past clutter and decor) i have been to houses that have been disgusting inside - haven't seen a hoover in months, and no effort had been made to tidy or 'stage' a room. it meant that while i could appreciate what the house COULD look like, it put me right off it.
for selling tips: lay the dining table out as if for a dinner party and let buyers know how much fun you've had having parties there. tell them about nice neighbours, proximity to schools, transport, shops, nightlife etc anything that you would like to know if you were buying it. let them know if anything is fairly new (e.g new kitchen, bathroom, carpets, bolier etc)
good luck