I tend to rely on body language for a lot of things.
It helps me to read people. I use it to emphasize what I'm speaking about. I use it when I'm not talking- a lot. Because, let's face it, I don't do much talking on a daily basis. I'm a rather quiet person. But people "get me" because of what I say physically.
I may be a bit of a hypocrite for what I'm about to say here.. but I'm speaking about a learned experience, and working on this on a daily basis.
No matter how clear you think your body language may be, it just may not be enough. You cannot assume someone is going to get the hint. If you have something important to say, say it directly. Because let's face it- not everyone is observant and/or understanding of visual cues.
If you like someone, tell them. If you're not interested, tell them. (That is, if you want to make it known.) It will save a lot of time and hassle, and you won't have to spend many a night wondering, OMG, did he/she get it?
Just fucking say it. That's all.
Unless, of course, you're purposely playing games.. which is totally cruel.. but the thrill of the chase is the most wonderful part of the bonding process. Use that power wisely.