If a decent-looking guy came up to you smiling and making eye contact, initiated a conversation, and was polite and friendly, would that be enough to pique a girl's interest, notwithstanding anything else about the guy?
Do the eyes and smile make that much of a difference?
Of course, its the first form of attraction, BUT, then goes straight to your personality afterwards. If you aren't hitting on all levels or even most levels for her then chances are she will lose interest fast.
Yes, a while back there was this guy I would see every day and I never really noticed him but one day we did that thing where both people go the same way and you can't get past each other and he gave me a sweet smile and was like "sorry." I ended up liking him just because of his smile and the honesty I saw in his eyes :)