So some decent advice. Now some sad reality. Some issues one may encounter in low level dungeons. Now is everyone is so overgeared, even with level synch. If using the DF for dungeon runs, and you get high ilvl players. Until you start getting into lvl 45 or higher dungeons you are going to have a b*&ch of a time maintaining aggro on anything, and you'll go nuts for trying, especially if you don't keep up with your gear. Alot of people who get into the DF at high ilvls are just there to get it over with. Alot of people no longer care about waiting for tanks to lead the way. Hardly anyone will care about marking as it wastes time ( I don't even bother with the wandering aevis anymore, mob is dead in seconds) and the party will most likely steamroll the dungeon. You may get some practice at using rotations and CD's, but by the time you figure out whats going on the mob is dead.

This is just something you may run into and be prepared for it. Pre-50 may be a bit discouraging and stressful. But if you get through it, tanking is alot of fun, or atleast I think so. Good luck.