1. Talk to him/her, and if he/she listens to you without interrupting, and makes few comments, he/she may be interested.Also,if he/she talks to you even when he/she is not suppose to be on the phone, he/she probably still likes you and is sacrificing himself/herself just to spend more time with you.
2. Wear new clothes or clothes you know he/she likes around him/her and see if he/she makes any comments like 'Nice shirt, is it new?'. Actually, any compliments are good.
3. Steer the discussion to the subject of your breakup.Ask if he/she thinks there is a chance you two could get back together. Does he/she ever say things like, 'What was I thinking?' (referring to the time you guys broke up) or 'Yeah...' or he talks about how "we had good times together" and sounds distracted by remembering the fact you aren't together anymore? If so, then that's a sign he probably still likes you.
4. See if he calls you a lot just to say hi. This is a sure sign of interest. If he told you he'd call you at a certain time but he doesn't, he might call you at a different time and start explaining why he didn't call you at the time he said he would.
5. Talk about other guys/gals and see how much interest he takes. If he asks you often who you like or if he gets really quiet, he might be jealous. If he asks your friend questions about who you are interested in now, if you talk about him, or other questions like that, he most likely want you back.
6. Ask him/her who he likes, and if he doesn't respond, doesn't want to tell you, or immediately changes the subject, it's probably you.
7. He licks his lips whenever he sees you
8. Look at him/her in his eyes, and if he looks back (for more than two seconds), that's another way to tell.
9. Flirt with him/her, but not too much, and see if he flirts back.
