1/2 NL (6max) dealing with the maniac

[numb3rs]

I have the best seat in the house, right of the player who's 84/80/1.5.

He open raises every hand to 6x the bb or $12. He continuation bets a lot of the time, but not always. He does raise, check-fold a fair bit.

This seems like it should be obvious, but I didn't end up doing well against him. How should I go about extracting the most money?

How often should I cold-call? How often should I 3-bet preflop? What's a decent 3-bet range vs LAG?

He seems to be a decent player post-flop.