You don't want to over due it because you are putting a lot of stress on the tendons on the inside and outside of the elbow. I do them 1 /week. One day I do pull ups with a towel on a pullup machine with counter balances. 2/3 sets of 10. The other day I do inclined pullups using towels wrapped around a bar about 3' off the gorund. Usually a weight rack bar works perfect. THe towels put more emphasis on gripping.
Deadlifts with both hands pronated. Towel pull-ups. Farmer caries using pinch grip on 45 pound plates in each hand. Captains of crush (look it up). Dead arm hangs. Twist-ups (rid with rope attached to a weight; roll it up to your hands and back down).
I like those. Deadlifts are the best imo (they are also one of the Big Three lifts) 
Those are great also. I use to do twist ups too. I just want to emphasis do not over do it especially using weights/body weight. You can develope tendonitis on the outside/inside of the elbow and getting rid of this put me in PT for about 3 months with 2 cortizone shots about 5 years ago. Took 5 months to heal and no judo/BJJ during that time. If you tear the tendon it is 9 months of healing after they reattach it he bone(surgically). I am 100% today. Use moderation in these exerises.