I also found sticking to a general color scheme (earth tones for me) to be SUPER helpful.
I keep my everyday wear, special occasion only items, lounge only items, and gear all in separate places (either their own dresser drawers, or the sides of the closet). Keeping it all together really didn't work for me because I would see something I hadn't worn recently (like a fancy black dress) and get caught up thinking of how I could dress it down to make it work. But I can never make my fancy black dress school/work appropriate, so I don't keep it with my everyday clothes.
I also have focused on only buying pieces that I love AND that are versatile. I need to be able to wear something several different ways for it to gain entry to my closet. I haven't been quite so ruthless with the things I already have, but the wardrobe I'm building is becoming smaller and more cohesive every day. The best part is that it doesn't feel like I have less clothes, because I'm actually wearing a wider variety of outfits, because I can mix and match more than I could before!
Do you know about the 30 for 30 challenge? http://kendieveryday.blogspot.com/ started a 30 day challenge in which she only wears 30 items (including shoes, not including accessories). She's doing it for the third time now, and 337 fashion bloggers, a couple of the YLF ladies, and myself are all doing it too! Hopefully it can provide some ideas and inspiration.
Finally, if you have some time, search for the word capsule in the forum section - there are a TON of great threads on this!