The right way to practice....and pulling off.

When you pull off, it's usually helpful to pull the strig a bit. Sometimes you want the note to die off quickly, but most of the time a pull is in order.

As for the pull off, I recall my first problem was trying to do the opposite of a hammer on (e.g., a hammer off). That didn't work at all. What you really need to do is pull your finger down -- rather abruptly -- toward the floor and partially away from the string. It does take some practice -- for me, much more than the hammer on did.

I tend to think of "raking" the string as I pull off, you are almost plucking it with your left hand on the way down.

As for practice, I find that I want to have a distinct purpose in mind when I practice. You mention chords, If I'm practicing chord changes, I'd get out my song or chord progression and sit down with the metronome. If I can't make the changes at 60 bpm. I'd likely turn the metronome off and just rehearse moving from one chord to the other, until I can change at 60 BPM. Then I'll work it up to whatever tempo is needed.

If it's something I find boring, like running scales, I'll set a time limit -- 5 min. 10 min. -- whatever, turn on the metronome and go to it. I'll always jot down what my current metronome pace is for a given piece/scale, etc.

I also get play-along type of materials. The best for me have tunes played at different tempos 100, 150, 200. I work on my own until I'm up to 100, then turn on the CD and try to play along. For me the two keys to practice: have a purpose (e.g smooth chord changes), have a measurable goal (changes at 100 BPM).

I should note that I'm also good for undisciplined practice, wherein I'll run through chord changes on the guitar while watching a football game. Obviously, not the best way to practice -- but it makes the football game more interesting. :D