Search Results: getting his attention

I know he liked me in the past but he never asked me out so I grew bored and lost interest. But I like him again now and I have shown signs of interest and flirted back with him so I know he has somewhat of an idea that I’m interested in him. Sometimes, he will be extra flirty and make his interest super obvious but then on other days he seems to avoid eye contact and then at other times it’s like he’s trying so hard to get my attention. He flirts with me more often when I reciprocate and when I act like I’m not interested I notice him looking/stealing glances at me more and showing up to places I’m at to be near me and we will catch each others eye but he doesn’t try to flirt. By flirting I mean he locks eye contact and smiles while gazing at me or trying to talk to me indirectly through a group setting. I cannot tell if he is shy or just playing games because I’m getting so many mixed messages.

At first, he came on strong and was really flirty. But it made me nervous cos i thought he was just leading me on or joking etc. I didn't think he was being serious.
Now all he does is stare at me. But he's staring at me less and less... and now he's paying less attention to me.
All i wanna do is say hi to him and start a conversation, but he looks unnaproachable most of the time and is friendly with everyone else, except me. I thought he was losing interest, but he still gets jealous when i talk to other guys and asks people about me.
What should i do? I don't want to look like a desperate idiot!!
Should i just be friendly to him and say hi? Or smile? I don't want to make it too obvious that i fancy him.
By the way, he stares at my bum a lot! So maybe he was just interested in a hook up?

I also thought he still likes his ex girlfriend!

But sometimes he talks about me to his friends - i hear him saying my name, but it might be bad stuff, so I'm NOT gonna assume he likes me, cos thats stupid.