A smile here, a glance there. These telltale signs of flirting are almost always an indicator that a guy is interested in you. While some signs of interest and attraction are more obvious than others, how a guy interacts with you is a clear indicator of his interest in you. Knowing what signs of attraction to look for can mean the difference between confidently making the next move or questioning his intentions with you.

Making a concerted effort to talk to you may be a sign that a guy is interested in you. Whether going out of his way to say hello at a gym, or rushing to catch the door for you as you leave the office, making an effort to start a conversation is a good indicator that he may be interested in being more than acquaintances.

Eye contact has long been revered as being a strong indicator of interest and physical attraction. In a study published in the June 2006 issue of "Psychology of Women Quarterly," University of Connecticut researchers examined the gender differences in determining sexual interest. While men and women in this study shared differing opinions when determining sexual attraction, men in the study reported that they believed that long, direct eye contact was a clear indication of sexual attraction.

Some women may pick up on a guy fixing his hair or straightening his collar in the mirror as a sign that he is interested in making a good impression, but mirroring your movements and gestures may be a subconscious clue that he is interested in you. Mirroring your body language is a way of building emotional rapport with someone. Try changing positions, uncrossing your arms or brushing your hands through your hair. If he does the same, his mirroring-behavior may have given him away.

In a study published in the February 2012 edition of "Psychological Science," researchers at Williams College examined the effect of perceived sexual attraction between men and women. The researchers concluded that the women in the study underestimated the amount of sexual interest shown toward them by men in the study. If this same trend carries over to everyday life, the cute guy at the next cubicle may be waiting for you to reciprocate his interest in you before asking you out for drinks, even if you think that he is not interested. Similarly, this same study suggested that men overestimate how interested women are in them, meaning that some men may take your courteous smile as a sign that you are interested.