After knitting half the back
of the sweater, I've got the diagram of the pattern memorized.
Which is very good, because I can tell when I've mucked up.
A crochet hook is your friend! When you realize that the stitch
in which you're about to knit should be a purl one, but is
actually a knit one because that's the way you [incorrectly]
knit it in a previous row, there's no need to unravel the
whole row to correct the mistake. Why lie? When I first started
knitting that's what I'd do to fix a stitch that had been
knit the wrong way because I didn't know any better. Instead
of unraveling it all, simply pull the stitch off the needle,
pull on it slightly so that it comes undone, use the crochet
hook to redo the stitch as it should have been done and then
place the stitch back on the left needle. Yay!