Before you advertise your house for sale you need to accept that at some point you'll have to pack everything up anyway - so by starting now you'll be saving yourself time in the long run.
Start on one room first. Have three boxes.
- Charity shop stuff
- Broken stuff for the bin
- Stuff to keep
By decluttering you are removing most of the personalised aspects of your home. It may be that these are the things that stop other people from seeing themself living in your home. By removing your personal items you're making your home a bit more of a blank canvas and giving others the chance to see their own stuff in your home.
Keep a few personal items: family photos in nice frames add class to a room when places right.
Look at the walls too. If you've got dozens of family photos up you need to take them down.
The three box method is sometimes supplemented by another box which you put things in your are not sure if you should get rid of. Label up the box as to what's in it and put the date you seal it. If you've not got anything out of the box after six months then throw it away!
Remember to declutter the garage, shed, loft and utility rooms! These rooms are well worth sorting out to make sure your home is shown off to it's best.