Check out his pupils, if they enlarge when he looks at you, when you say something slightly provocative, he's interested in you. If he say's he likes/loves you, but doesn't really make eye contact, fidgeting etc, then he's probably spinning you a yarn. If when you take a drink, he picks up his glass and takes a drink rougly the same time, he's paying attention to you. Look for mirrored body language.
And remember, the words 'I love you' should be taken with a pinch of salt when said in the horizontal position!
Never kiss a fool and never be fooled by a kiss!