Previous tips were to buy cheap and to audition your clothes.
My final suggestion is to view your closet as more than just storage. It's another room of your house (albeit tiny). If you're reading a home design blog in the first place, you probably like design. So, design your closet. Being an aesthetic snob about it will motivate you to keep the socks put away.
Personally, my bedroom closet is a palace. My pantry is a swamp. That's because I haven't even tried to make the pantry pretty. If I had cute matching bins or something or shelf backing lined with wallpaper, it might be a different story. Maybe next spring. . .
Images: Creative Closetworks, Tom Andrews for LaList (Barbie's Dream Closet), Making It Lovely