Any interaction involves communication in two levels - verbal and non-verbal. Verbal communication refers to what is being said. Non-verbal communication refers to everything else, including body-language. When people interact with you, they are broadcasting non-verbal messages continuously. Do you know how you can interpret these messages?
In real life, interactions are often replete with mixed signals; people say something and non-verbally communicate some other message. It's no great wonder then many people in the dating scene are confused with what their partner was really feeling or thinking. Apparently it is a difficult task to try and understand this language. But once you get the hang of it, it can be quite easy.
Before you go on a date, you need to have a rough ides of the signals which will tell you whether your date is interested in you. The signals will vary with each people, but there are a few patent signs for flirting.
If your partner is maintaining an eye contact for more than five minutes at a stretch, you can take it to be a sign of sexual interest. Such a prolonged eye contact does not occur if the other person is just a friend or an acquaintance, but it is obvious between the lovers. So if you find your date looking into your eye for quite a long period, you can know that he/she is really interested. In case you catch your date throwing a glance at you and then drawing the eyes away, it should tell you that the person is surely interested, but is feeling shy to indicate that.
It is a common practice for a couple to touch each other while flirting. The touch might not always have a sexual intention as people do touch each other casually while giving a playful nudge or a loving ruffle. Even friends may touch each other now and then while they are flirting. But if you think that your date is continuously touching you, you can interpret it as a sign of sexual interest, and can take it as a provocation to move further.
So keep your eyes open for these signals while you flirt with your date. Though these are no official signs, they are enough to tell you how much you can get involved with each other.
The same signals or rather the absence of them can also tell you if your partner is losing interest in you. Say you have been dating somebody for a while and suddenly they start to show changes in their patterns of availability, attention to you, body posture or eye contact, or they suddenly become less communicative or restless. You should pay attention immediately to what's going on. If their verbal messages match with their non-verbal messages, odds are that they are losing interest in you.