In addition to stitch markers and counting I also suggest using a lifeline. That way if you do have or frog a bit you can just frog back to the lifeline if necessary.
A lifeline is a piece of finer weight smooth yarn, crochet cotton or in a pinch you can use unwaxed dental floss. On a row with no errors you put the lifeline on a yarn needle and thread it through the stitches on your needles. Make sure it's long enough it won't pull out! IMPORTANT- make note on your pattern what row it's on and how many stitches. You may need that info. You can add more lifelines as you go or move that one up, but always make note of changes.