The ideal is simple, keep Vol'jin and Natalie alive as long as possible and finish the game with Cairne and Diablo.

Open up with Vol'jin, Cornelius, and Natalie, in that order. After a death, it's situational but I'll typically bring in Cairne or Cookie.

Against Beast Opener (Rexxar/King Krush/King Mukla):

You almost always want to Shadow Shock Rexxar on turn 1 so you can get at least one more turn off with Vol'jin, otherwise King Krush can nuke him. Turn 2, I typically go Curse of Weakness with Vol'jin, Hold The Front with Cornelius, and Anathema with Natalie. Rinse and repeat until King Krush dies, then focus down King Mukla.