I use pins and my seams are actually pretty good, but on the last couple of quilts I've made I have joined the blocks in square or rectangular sections rather than long rows. So like if you have a quilt that is 9 blocks by 9 blocks, I would first join a 3X3 section in the upper left, then the 3 block by 3 block section in the upper right, then lower left & lower right. Doing it this way, you only have to sew one seam that is the whole length of the quilt. I find it much easier to control a shorter seam.
One of the board members (sorry don't remember who) also posted that they add the sashings and cornerstones to the blocks before joining. This also works great.
Hope this makes sense.