Hey all. In all the chinning articles I’ve read, this little tip never came up: look up. That is, pick a spot way up on the wall, ceiling, whatever, and pull yourself towards it. And keep looking up, don’t start checking out the bar once you get near it. That may have been obvious to some people, but it never occured to me until yesterday. Granted, I’m a shitty chinner, but it improved my numbers right away, so it seems to me there’s something to it. Someone more informed on the biomechanics of the movement can probably tell you why, but in the mean time, try it out next time you’re in the gym.
Looking up puts the chin up higher. That means you don’t have to pull your ass up as high.
If you do a search on this site for Zeb’s chin up routine you will find that is one of the tips he gives. Your right, it does work.
Here is another tip:
Do some overhead pressing. This is the antagonistic of chinning and pullups. It will increase your numbers.
Regardless of your chin height, you should pull as high as you can, hopefully until your collarbone brushes the bar.
Another tip: Try pulling DOWN with your elbows. I know it sounds strange, but I find that it makes the reps feel easier, so I can get a couple more.
Good tip - I think of it more as pulling down with my elbows with a nice 1 second back squeeze at the top 
Looking up also helps prevent the neck/upper back twinge that some experience when doing chins.