I haven't been on enough to make a proper guide, but here's an idea of what I would do.
You don't need steal AT ALL, except for that 1 point in it. Just forget about it, it's too little of a difference to even be worth the time. Max out HP and Attack buffs, then work on aura, SP, and that buff (which I forgot the name of) that gives you 200 increase in each stat for each 1 point invested in it (for 3 points total, 600 increase in all stats), this needs to be maxed.
Keep in mind this is only an idea, I'll take a look at the actual numbers later, whenever I can get online.
Edit:
[Image: http://img33.imageshack.us/img33/6361/dkstats.jpg]
As you can see I messed up my DK a bit, but this was back when even Glas wasn't out yet. Old stuff. So, you'd want to max out Revelation: HP and ATT first for maximum potential, have 1 on steal, max out SP recovery (Slashing high/Furious 7) then choose between going pure resistance or pure aura, resistance is useless if it only works half the time.
For now, I recommend getting aura first, you need that Revelation: Potential maxed out ASAP. Any spare PP can go into Aura/resistance, or even into the "Steal family" if you want, if you still need to apply PP before getting the second transformation.
Second transformation stats, same thing, in a sense. Max out ATT and HP, then choose between Revelation: Vigor and Fissure.