I've never tried it on someone of the same sex, but what I have read is that it works a lot better on women than men (women tend to be more receptive to energies). So if it's a girl you want to try it on, it'll prob even work better/faster.

I wrote this in another thread I think. I had a girl friend who tried something similar on me. It wasn't PW (she doesn't know the technique), but she wanted me to ask her out as like a manifestation experiment so she briefly visualized and wrote down the intention.

When I met up with her the following day, a thought bubbled up in my conscious, and I thought - why not ask her out to this event I've been thinking of going to. After I told her, she laughed super hard and told me what was up.

So something similar could happen with the girl you're interested in... she might start getting thoughts like she should be friends with you and it'd feel completely natural.