You can be sure that a girl likes you by noticing her behavior when she is close to you !!
One of the things that makes it evident is the nervousness that you have when you are close to you, if you get to notice that, it can be a signal.
Another sign is if the girl laughs when she is with you, usually when a man likes us we laugh at the things he says, either because we like it or because of nerves.
A very important signal is the visual contact, that is, both eyes agree, and at that moment only both will be able to know if there is a connection or not. In my case I usually look down when there is eye contact product of the nerves, that also happens to many girls
Text messages are important, because in daily conversations you get to know the person more and so you can find out if he likes you or if he likes another person.
If she usually touches you when she speaks, be it an arm, hair, face or if she gives you spontaneous hugs is a good sign to know if she likes you
see if he flirts with you, if he moves his hair when he speaks or if he bites his lips, or simply tries to be sensual and pretty by being with you
Something IMPORTANT is to know how she acts when she is with her friends, because not necessarily the aforementioned means that she flirts with you, since it depends on the personality of the person, if she is affectionate with her friends, just as you may only be a friendship, but if you have that deal just with you you can be sure that you like it
Now those are things that you can notice but the most important thing is that you are sincere, tell her what you feel if you see it necessary, but do it at the right time, and with the right words since if it corresponds to you then congratulations, but if he does not , try to continue that nice deal they had if it becomes uncomfortable.
Sincerity is the best of all, it opens many doors and eliminates doubts.
There are a lot of ways to determine if the girl likes you or not.
One obvious matter is time. If she allocates some of her time (or probably most), then that is the first attestation of liking you. Girls do things that makes their time worth. If you're not worth their time, they'll show you some laziness to reply and unwillingness to continue the conversation.
Another thing is she talks a lot. This really means she is comfortable talking with you. She doesn't care what she talks. She likes the feeling of talking and sharing things to you. That is another sign that she likes you.
Another important thing is being clingy and trying to grab your attention. If she starts being so close to you, showing some nice gentle touches. She surely likes you. Her being close to you is a pure attestation that she likes you.
She is very proud of you. She keeps praising you and your achievements in life. She likes to talk about your success and plans. She keeps very interested with your ambitions and goals in life. She wants to talk about future or what are you planning soon.
Last, you can feel it. The way she acts will be very obvious and the most important thing that you should focus. Feel her. Feel everything that she makes and try to understand her movements.