If you want to develop not only your back, but a strong core as well than you have to start doing pull-ups. I’ve mentioned it before, but I can’t stress it enough. Functional training methods using only your body weight truly test your central nervous system and can be a lot more challenging on your body to handle.
Here’s a tip:
Start doing pull ups every morning and every night for a full month. Now there are several variations to pull ups. Wide, Neutral, Close Grip, Reverse Grip, etc. Just focus on mastering one technique before going to the other. Even if it’s just one pull up a day, you will see great progress come the end of the month. If you can’t make it to the gym to do pull ups than try getting yourself a cheap pull up bar that you can put in your door way.