Most Helpful Girl
If she puts an effort into conversations that the two of you have. if she actually tries to start conversation with you without you having to say much then she pretty much enjoys your company. when a female tried to unite a conversation with a male constantly 9 times out of 10 she enjoys you. Its also about body language when she is speaking to you.
Most Helpful Guy
By chatting to her, if she asks you questions back and is friendly then things are cool, if her body language is close and she just say yeah or no then she ain't interested.