On this, Chase was right. Treat her just like you would any 'good friend/male roommate.'
I've had a couple of female roommates...interestingly, both were lesbians...although not full fledged ones, I guess.
They both lied to me, but I'm glad they did.
Be very cool...and she'll start wearing less and less around your place until she's practically screaming 'take me, hold me, love me, no, not there.'