I respeced to Circular Breathing right at the start, along with Chant of Resonance and Exalted Soul… but it took me half the game to remember that one rune in Sweeping Wind generates 3 spirit/sec when at 3 stacks. And you’ll probably want to put some joy into Kormac’s life by sitting Lyndon or Eirena in order to get his GLORIOUS resource regen passive.
I hesitate to call it “strategy” since a character well-geared for Inferno can instantly obliterate anything in Nightmare, even on MP10. The strategy then is mostly about maximizing your Magic Find and movement speed. And you want to kill things with skills that don’t require you to stop, or even slow down. A Tempest Rush Monk is pretty much ideal, since you can kill everything with a single pass and your movement speed is rocket-like.
Bear in mind that skills that require you to hit or crit enemies aren’t going to work so well since everything dies so quickly. TR (db) is great since it can be entirely fueled by spirit generation gear. A Sprint Barb would have more trouble, and would require very high Crit Chance for the cyclones to proc enough to maintain Fury.
We are leading of Diablo 3 Power Leveling and Diablo 3 Gold provider.
Also remember that it’s very easy and there’s no danger, so you can switch to odd skills you’d never use in Inferno purely to get more movement speed or resource regen. This is part of the fun, just for the variety in the play style.
While it’s fun for a change to just rush through levels like a madman, you will miss the monster density you’re used to from Inferno. Act Three isn’t so bad, but Acts 1 and 2 are dreadful for sub-Inferno farming and you’ll get that “Why aren’t there any monsters on these levels?” feeling all the time.