I am knew to knitting and I often pick up part of another stitch and this creates a small piece of loose yarn. Is there any way to fix this?
The best thing to do is to watch each stitch and work carefully. Sometimes however the yarn is a bit difficult to work with and tends to split easily and sometimes you just make a mistake.
Look at your knitting after each row so that you can correct mistakes early. You can tink back if its on the current row or ladder down to correct them.
If you notice a little loop of missed yarn, you can also use a crochet hook to pull the loop to the back of the knitting and out of sight.
Jan just posted a link to some very nice suggestions for correcting mistakes.