Trait after every corp charge you land- the exception being characters who can wakeup with a multi-hit which disables your shield and also hits you regularly afterwards (DeathStroke, also, Green Lantern's chain gun).
He has the farthest reaching Jump+Hard attack in the game, after every Jump+Hard you get a free corp-charge because it can be executed in the air. If people are trying to play the jumping game on me, I remind them no one beats Lex's jump 3.
I am awful at footsies with Lex- maybe it's just because I suck at it, or maybe it's because Lex is awfully slow, but I get shut down on that. Hopefully others can help with that.
Lex's closeup combos use meter-burn gravity-pull, but it's awfully unsafe. I never cancel into gravity pull unless I have a shield, and the opponent is vulnerable because he/she just tried ineffectively to hit me through the trait.
If the enemy is in the corner far from you, and you have your shield on, meter-burn your "target acquired" attack until you haven't a drop of meter left- after your last hit with it take advantage of the time you have to trait and dash, or whatever setup works for you. For some reason, I've been able to spam "target acquired" with meter burn on any cornered enemy (so long as I begin with my shield on) and have yet to see an enemy get out of this chain- I'm not sure if it is possible to or not, but I've yet to see someone get out of it once I've started. I do sometimes take wakeup ranged hits, but I'm able to keep spamming anyway.