Well, I am finishing a rather bulky sweater in a fuzzy, variegated yarn. So far, I have sewn on the sleeves and done mattress stitch to seam the sides - with fairly passable results. The problem is the sleeve seams. The sleeves are narrow at the cuff, and then increase in width through the length. It looks like something of a staircase along the edges, and I don’t presume that a mattress stitch would work in this case since one would have to keep jogging over every few rows. How is this usually handled? With a back stitch? Or do you do the mattress stitch anyways? And do you start at the cuff or the underarm? I’ll take all the advice I can get. This is my first sweater, and I don’t want to ruin it on the last step! Thanks 
Sleeve seams Help!
I always do mattress for the sleeves, too. Yes, you will have to keep having to jogg over every few rows since the sleeves get wider as you go up, but it’s your best bet.
I always start at the cuff and work my way up, just in case I mess up and the sleeve doesn’t come out perfectly even. Any glitches can be hidden in the armpit. Who looks there?
Thanks, Ingrid. Wow, that was quick! I guess I can start on it tomorrow. It’s going to be a little challenging (for ME) since the pattern is slip stitch rib-not stockinette. Not sure I’m going to be too adept at keeping track of what row I’m on…