When I first started knitting, I had a real problem keeping track of which stitch I was on, and this made the rib stitch especially difficult. That is until I realized that the knit and purl stitches looked different. That was one of my great "AH HA!" moments. Now I'm so used to looking at these two stitches that I don't even realize that I'm doing it, up until I read a post by a fellow blogger. When she mentioned messing up her ribbing it brought back some memories of me doing the same frustrating thing! I know there are probably tons of people who have already put up some helpful pictures/tutorials for this, but I figured I would just put up a simple picture of each the purl stitch and knit stich.
If the stitch looks like a 'V', then it is a knit stitch. When working a rib, then this means you are going to knit this stitch!
If the stitch is bulging out, then it's a purl stitch. This means that if you are doing a rib stitch, you purl it!
So those are two pretty simple pictures, but next time you're knitting and you're not sure whether you need to knit or purl, just remember that the 'V' is a knit and the bulge is a purl! Hopefully this will save some frustration for someone!