it is one of the #1 giveaways you're into someone, or that you simply have interest in someone, but some girls like myself tend to be cautious and try to stay away from players, orrr theyre just confused and don't know what you really mean by your eye contact, so if you truly like a grl and want to know her more, and you make eye contact and she smiles back and is responding good, you as the guy should be consistent with your actions, and take her making eye contact back to you/smiling as a go signal for now doing step two and actually talking to her, asking her out, making convo...taking it further...etc
I would say yes. Even more effective before you've met the person and just want to get their attention. I've found that 99% of the time, just making eye contact with a guy I want to meet and smiling a little is all it takes to get them to come over. Same with guys. If I suddenly noticed a guy making eye contact with me and looking like he's interested, I'll be more receptive when he comes over.
It's the best way if you're shy and I think it's the best way to get someone's attention. But some people make eye contact for other reasons-i'm wary of guys that always make eye contact because if they liked me they'd come and talk to me but since they don't I'm not sure eye contact actually means anything. If you follow up the eye contact then yeah that's a pretty good flirting technique because like I said-it's the easiest and quickest way to get someone to notice you.
I guess wheb you first meet someone you don't go for eye contact you just try to be funny and then as it progresses that is when the eye contact begins... I think that there needs 2 be eye contact when you like someone , and then I guess usual flirting