I've noticed my pets tank better now that I'm a Demonologist, but that's mostly because I don't have to worry about drawing the aggro by healing them so much (my liche is 4 levels above me). When I have any of my pets tank, I let them attack first, of course. Then I'll generally cast a spell that takes time to cast, letting the pet get more aggro. Even when I use the instant cast spells, I'll allow a moment between them, because if you attack too quickly you'll pull the aggro to yourself. I often don't bother healing them until they're down to halfway on their hp, because healing them seems to draw aggro faster than hurting the mob/boss. Use the attack spell that calls for charges occasionally; your pet will attack faster and draw more aggro that way.
There are talents you will get as you level that will reduce your malice, and there is a mastery that also lowers it, so max that one, definitely. Hopefully some of this helps!