What's the best way to seam when making bulky yarn items? My regular seaming makes a bulky sweater even bulkier.
I haven't had to do this, but I've heard that you should use a thinner yarn in the same color as the thick one for seaming.
Not sure about the seaming itself, but using a thinner yarn might help.
What method do you use for your "regular seaming"? Mattress stitch and thinner yarn, as Cindy said, should work well.