Personally, I would never simply go looking for a girl who 'does drugs,' even though I understand the appeal. If drugs, epsecially mdma, lsd, etc, have had a strong influence on you, then those experiences are ones that you can share with her gradually, over time. Girls who are smart, worldly, and open-minded will, at the very least, appreciate you for the vicarious experiences you share with them about your use.
They may not also choose to do such things, but to me, having a girl understand that drugs have had a positive influence on my life is as good as having a girl who will use them with me. The best relationships are built on communication and respect, not just getting fucked up together.
I recently met a girl who was totally straight, and after some time, I confessed to her my mdma use. At first, it was awkward, but after a few conversations, hearing her say to me one night while lying in bed "so tell me about ecstasy......I know it means a lot to you....I want to try and understand...", well that was soooooooooo much more rewarding to me than if I just found some raondom chick who rolled every weekend...