pull offs

when i do pull offs i pull the string down a bit to keep the sound but when i do the pull off the sound of the new note is a little off, anyone have any ideas how to keep the sound constant?

You can try instead of moving the finger down and then lift it, to somehow "pick" the next note. By this instead of making two movements do a diagonal one with which you are giving strength to the next note, but not changing the initial pitch. To see an example try picking with your pick hand's middle finger an open string. Notice that if you move the string and then make it sound, it won't sound to good, instead if you do the diagonal movement, it'll sound better.

Yeah, don't try to do a pull-off by bending the string down until your finger pops off. And try not to move the finger that you're pulling off to.