I try to make it less overwhelming by tackling one room at a time. For each room I make piles of:
Anything in the keep pile I go through again and try and put in a Toss, Sell or Donate. If it made the maybe keep pile in the first place it probably wasn't that important anyway.
I have quite a garage sale pile already and wish it were Spring so I could have the sale. Will keep you posted on when it will be. Lots of:
Small Kitchen Appliances
Bathroom and Kitchen Supplies
Books and Games
Mens Womens and Kids Clothing
Doors, Misc Building Supplies and Underlay