I was hand quilting in a 16" hoop for the longest, and some times with no hoop at all. This past fathers day, my wife and son gave me a new Grace Z44 hand quilting frame. Quilting on this frame has made a huge difference in the quality of my stitches. The tension is perfect, and it holds it just right to quilt on.
I use to draw a line with a ruler, then hold the ruler next to the line and make my stitches go in or out every 1/16 of an inch. This gave me 8 stitches per inch. I practiced this and once I could do this without the ruler, I could still get 8 stitches per inch, and even moved a little tighter to get about 10 stitches per inch. This is tough though. I found that by not using a thimble, I could get better stitches, though I've not found anybody else that has the same results.
Good Luck.
Steve