The DM suggestions are based on sneaking through to a few specific location that have non elites for you to aoe farm and reset the instance. You can youtube those guides, but i'm pretty sure most of them arent as viable as the video suggest since DM classic is quite different than the private servers suggested. Though, i havent been in there yet on live, so i truely dont know how different it is.

At 56 i'd be in Eastern Plaguelands doing argent rep and clearing the zone quests, or BRD.