When doing lace work, use a life line.  A life line is scrap yarn threaded through a row, so if you make an error, you can rip back to that scrap yarn and pick up your stitches.  I recommend threading a life line on the first row of a pattern, so when you rip back, you know you will be knitting the second row.  To place a life line, thread a contrast yarn through a needle and draw it through a row.  (Some circular needles offer a hole to thread the yarn through and it draws the waste yarn through as you knit the row.)  There is nothing worse than trying to pick up yarn overs in lace work.  Life lines are life savers.