Re: your number one technique
If you're uncomfortable enough to be trying to guess from someone's eyes whether they're going to take a swing at you, pre-empt it and take a step back so they'd have to come to you in order to do so. Heck, take a couple of steps back and get your hands on a weapon of some variety.
It's very easy to tag someone in the dead-space where they're having to come to you but haven't quite started to present an immediate threat yet. There's no reason you should stand there playing "guess the mind-state from the eyes." If you feel that threatened you should be using the time to set yourself up to win a fight if it does happen.