Saying "I like your shirt" is too bland and boring to pique anyone's interest. You need to start trying to notice unique and interesting things about the people around you. I do this when Im commuting or shopping or whatever and just look at people, anyone, and try to notice something about them. Do they look shy, confident, do they seem happy, concerned or worried, maybe they look relaxed or calm. They could be wearing a particularly striking piece of clothing, maybe brightly coloured or unusual. If you can adapt it to them it will at least capture their interest, even if for a second. Say you see a hot girl who you read as being in a very bubbly mood, stop her and make that observation.
Also remember that its 30 per cent what you say and 70 per cent how you say it.