every time i knit i notice that my yarn twists, i dont know if i am holding the yarn properly or if i am knitting incorrectly. please help.
This happens with some yarns and not so much with others. It may be due to the way the yarn is plied and not to anything you're doing at all. Every now and then stop, push your knitting back from the point of the needle, and let it dangle from the ball of yarn to un-do the twist.
Here's some more information from a crochet site but it applies to knitting as well: