Well, usually flirty eye contact and smiles help. It depends on the guy though, some want intelligent conversation while others just want to look at you. If you know he's really into something look it up, if you find you're interested as well theres a great conversation starter. However, if you're not into it, don't pretend to be, that just pushes them further away.
If you take out time for the guy more than your bf. This indicates that you like the guy more.
You like a guy more when they ignore you because when hes not talking to you then you get anxious and you miss talking to him. So you tend to like him more.
The girl is usually more shy.
It means he sees you, that he is looking at you, that you are in his line of vision. Nothing more.
If that happens, you should question which guy you like more (the one you are with, or the other guy) and decide based on that.
Be likeable.
Talk to him more.....or move on and find a guy whos more interested in you
Find out what the guy enjoys to do, perhaps you share the same hobbies. Talk to the guy about these hobbies.
Then find out which guy you would like to date by comparing their pros and cons.
Maybe you like him more or are more physically attracted to him
get 2 know the guy more.
Tryand talk a little more about it