novaknitter, I have to agree about PGR's instructions. They're a bit confusing at times.
i.e. she would say "your next two stitches should be yarnovers" and i'd be one off.
This happened to me too when I first did it! What I worked out was this:
When you start increasing again, you knit up to the first "pair" of stitches (formed by your yarnover on the previous row). The first stitch in the pair will be a knit, and the stitch after that is a yo. You have to knit that first stitch in the pair, otherwise you will always be one off.
I have included a picture with this post (hoping it helps)...