Touch is one of the most powerful indications of mutual desire. You're expressing interest if you touch her. She is attracted to you if she enjoys being touched by you. If you're walking next her and you bump into her a little bit, and she begins walking closer to you, that's a sign of interest. If you keep your hand on her shoulder or in her back pocket, then that's another sign of interest. If she pushes your hand away, then stop touching her. Don't be upset by this reaction because the girl doesn't want you to touch her. Also, notice how when you first start talking to a girl, sometimes she will not pay attention to what you are saying. But soon enough, she will start laughing at your jokes and smiling at you. That's because you were able to get her attention with your hands. Finally, never go beyond the limit of consent. If a woman says no, then don't ask again. It's as simple as that. Never force yourself on a girl if she doesn't want you to do so.