Be yourself and say hi when you walk by or smile. And you can try flirting with other guys around him. And if your friends with his friends then go talk to them and make him talk to you first and make him make the first move.
I hope this helps, it doesn't always help with all guys but don't look like you trying to make him jealous cause then the guys normally just give up. There is a balance that may be hard to find but I'm sure you'll be able to do it =]
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