If you want to not lose aggro on MRD:

Level Archer to 4 and level Pugilist to 12. Crossclass Raging Strikes and Internal Release.

Internal Release is less necessary now, but you'll eventually need it as it's the only offensive crossclass for WAR. Raging Strikes, on the other hand, is only usable by MRD/GLD but is a really nice boon for damage (and consequently aggro gen), especially on single target where you really only have Skull Sunder until much later.

MRD doesn't have as much trouble as GLD, but I found Raging Strikes to pretty much alleviate any issues I had. All the other tips in this thread are equally spot-on, I just didn't see anyone mention this. P: