Ensure that you have a place where you can practise them throughout the day.
So maybe buy a pull-up bar for your house unless you live near some football goals or a suitable bus stop for doing pull-ups?
Apparantly a good method is the "greasing the groove" method.
If you max is 3, then try doing 1 rep every time you walk into or out of your kitchen (if that's the doorframe where your pull-up bar is fitted.)
If you go into your kitchen 20 times in the day, then thats 20 pull-ups in a day, but you hardly notice it. Then increase the reps as they become easier....
Muscle Memory, Simply practice...
I been lifting weights for 3 years, and since now i struggle with pullups... Since buying chinup bar from powertrainer.co.uk, i literally have gone from 3 pullups to 6 pullups in a week, by practicing each day every hour or two im in the house... practice is key
i went down my gym today and found a proper pull up aid machine its brilliant i dunno why i never noticed it before but no one really uses it the gym i go to is were all the proper body builders go so they dont use it but its really good u stand on a platform and it goes down to the floor and then u start doing pull ups and the platform has weights on it to push that up as well to aid you doing pull ups its really good *text deleted* go down there and do a load on it each day now as well as my normal stuff and each week take 5kg of until i can do a decent amount unaided then carry on with unaided once i have it on 15kg at the moment
Yeh climbing is really good for that. And for forearm muscles! We always had a challenge of who could climb the highest on a shallow overhang with arms only. Really good burn in the forearms afterwards.
Those pullup aided machines are apparently very good for improving your pullups. I've never used one, but having spoken to my self-appointed fitness instructor, he was singing their praises!
I have a different view to some of the people who have commented on how to increase your pull ups, try both ways im not sayin mine is best.
I have been weight training since I was 13 and im 20 now, i trained competively as a bodybuilder for 4 years, this has helped me extremely and I have heard just about every technique for increasing strength on pullups, press ups, sit ups, bench press...etc..
In my opinion the best way to increase your strength for pull ups is to do them twice a week. If you do them everyday, you run the risk of overtraining your latissimus dorsi, this will only dent your progress.
Also, you should follow a program for each muscle involved (as previously mentioned), as well as the rest of your muscles, so your not imbalanced.
Here is a program you could try..
Whatever your max is, do one or two less each set.
Monday and Thursday
5 Sets of pullups, doing your chosen rep range. (Do the same amount of reps each set, even if you get tired and cannot complete the rep fully)
The next week you should try and do one more rep than you did last week on your first set.
And again for the following week, and so on...
P.S This is only what you should do for your pull ups, you should incorporate other exercise for your back in your workouts too.
There is only so much information you can type into a forum and I have only tipped the iceberg for strength training techniques so if anyone wants any help feel free to ask.