It all starts with the eyes. You walk in and your eyes lock. The ‘half a second longer than usual’ almost always means something. A woman has an uncanny ability to absorb a lot of information with a single glance. If you catch that glance, more than once, then she definitely wants you to know that she has noticed you.
If she is shy she might not say much. She might simply carry on looking directly at you and looking away, hoping that you will be the one to make the first move so she won’t have to. Once you can get a conversation going, that’s when you need to put your observation skills into practice.
Some women are fairly outgoing, so they won’t mind playfully hitting you during conversation; or placing their hand on your arm in an “accidentally on purpose” fashion. This is a subtle way of flirting which often increases the man’s eagerness. The trick is not to get carried away, some girls might just genuinely feel comfortable around “any guy”, and this is usually the case if the girl in question is good looking.
Pay attention to where she leads the conversation. Generally speaking women are more comfortable talking about themselves than men; but if you discover that she seems to be asking a lot of questions in order to find out more about who you are, then she is certainly intrigued at what prospects you might have to offer.
A lot can be told through body language. If she is interested she will make sure eye contact is maintained throughout the conversation. If she is fidgeting, looking around, or seemingly unsettled, then she is either shy, has a boyfriend, or can’t wait for you to go away.
If you can go as far as getting her number, that’s definitely a good start. An even better continuance would be if you called and she could still remember who you are. If she can’t remember you, that’s definitely not a good thing. A bigger testament to progress would be if she calls you back, then you have definitely done something right.
All this is purely on a superficial level, call it attraction. When one is dealing with love, it requires a whole new evaluation process which can only be truly accurate over a long period of time. But we all have to start from somewhere; a girl that doesn’t like you, is not likely to love you.