Clothes: Winter clothes- anything I haven't work in this last season gets donated Spring Clothes - anything that is 'shot' or doesn't fit, or just isn't 'me' anymore gets donated * Repeat in the fall * :)
Knick-knacks: Look over knick-knacks and see what is 'special' and what is just 'junk' - keep what I want and throw away things that have no special meaning to me. Some special things may go in boxes or it may be displayed, but I go through EVERYTHING at least 2x a year. Something that was special 5 years ago, may not be now. Some knick-knack may be special but not for decoration (i.e. my cousin's favor and matchbooks from her wedding - I can't throw her away, but I don't want to display it either, so it goes in a rubbermaid until a special anniversary!)
Go room by room and clean corner to corner slowly ... take awhile - more than 1 weekend but soooo worth it!