I found this great tip for an easy way to de-cluttering your closet - turn all your hangers around on January 1st. Once you wear an item of clothing turn the hanger the other way. Every few months look at all the items you haven't worn & make the decision to either donate or recycle. (This would exclude some seasonal items.)
Bonus tip: Using all of the same hangers in your closet helps to make the space look more organized and unified. All your clothes will hang the same and having all the same color hangers reduces the visual clutter. If your closet walls are white or very light colored, white hangers will disappear against the white backdrop giving the illusion of more space.
Another area that seems to get quite unruly very quickly is the linen closet. I have found that the easiest way to organize a linen closet is to group like items together - towels on one shelf, sheets on another, etc. Then use bins or baskets to contain all the small bits - extra toiletries, face clothes, candles, etc.
Bonus tip: Using all the same bins or baskets helps to create that cohesive organized look. Labelling the bins or baskets also helps to quickly and easily identify what is where.