<p>Lifting daily was the best thing for me. I went from 12 pullups max to being able to do 30 now. Before doing a back workout, I always do 3 sets of pullups and try to maintain the same amount or more each time. I think I started out at around 7 pullups per set, and eventually have gotten it up to around 15 per set. </p>
<p>I recommend doing this twice a week, among other exercises (lat pulldowns and rows) if you want to significantly improve. Then when you want to see how many you can do total, just take a week off and try it next time.</p>