You can decrease those stitches one stitch in, too, if you like. I usually decrease in a direction slanting towards arms. But you don't have to. And actually, more and more I'm liking decreasing on the neck edge at the very edge instead of one stitch in, especially if I'm going to pick up the stitches and so cover up the decreases. I like this because to me it looks neater, cuz even though you decrease always slanting in one direction, not every row is a decrease row, leaving some rows with slanting stitches and some rows without, and I kinda don't like this look. But I think the choice is up to you.