Some people knit flat for 3 or 4 rows and then join the work. Maybe that would help. (You use the tail to seam that short edge later)
If the hats are knit in the round and don't have a flipped up brim you can use the method I worked out for nice tight ribbing. I always use it on ribbed hats.
I figure this out on my own, but I'm sure I'm not the first to ever do it. Here's my old blog with the info.