You asked what the BEST stores are for buying "girl clothing" so you can cross dress. This might rule out the thrift shops mentioned. I've found good stuff in those, but it takes a lot of looking. The best would probably be Norstrom, which I understand has a company policy of being helpful to males wishing to purchase womenswear for themselves. I've never shopped there, but in Charles Anders' book The Lazy Crossdresser, he discussed going and was well treated.
Most of my womenswear, I've purchased online. I don't know why, but clothes shopping in stores bores me to death, yet I'm absolutely addicted to shopping online.
EBay is a great place to get good prices on almost any clothing item, since there's so much there and competition keeps the prices low. Also, the mailed package will probably be generic and not indicate the contents. My absolute favorite online source, though, is Newport News. Their lines seem almost intended for the crossdresser: lots of high necks, elegant long skirts, high boots, etc. Everything from them seems designed for the cool sexy-but-trashy woman.
Other good online sources I like are
JCPenny.com,
Metrostyle.com and Amercan Apparel. I've caught a few bra and sleepwear sales at
OneHanesPlace.com, too.
Lyric