Also a relatively unknown one, especially for yawing - make the control sticks longer.
They are in two halves, both screwed on. Unscrew the top half completely, then unscrew the bottom half up a bit leaving a few threads exposed. Then replace the top half and tighten everything up. It makes the sticks about 20% longer, and makes for much easier control when yawing. And it's free too.
Also, if you're doing this, you can turn the top half upside down so that the knobbly bits are smooth, if you see what I mean.