To build muscle you'll need to complete the eccentric portion of a lift. This is where deadlifts fall short. You don't exactly lower 300lbs in a slow and controlled manner. Deadlifts also tend to only work your back in an isometric manner. Basically any other exercise that has an eccentric phase should help. The back can handle quite a bit of volume when training rows and similar movements. Pick a couple exercises and do them for about 8 weeks before switching to different exercises.
If you're deadlifting then I'd stay away from bent over rows because your lower back will fatigue before your mid traps and lats. Pick versions that support your chest so all of your energy goes into the targeted muscles (DB rows with hand and knee on a bench, Incline DB Row, machines, etc)
Do 3-4 sets of 10. I've been doing 2x10, then one double rest pause set (max reps, rest 15 sec, max reps, rest 15 sec, max reps).