If shooting live subjects you might find a tripod and focus rail too cumbersome. I mainly use mine for ground-dwelling wildlife and for that use it handheld, with my left hand touching the ground to steady the lens at its end. I'll use either the MT-24EX, or a hotshoe gun on a macro bracket, so shutter speeds are not a problem, just getting accurate focus. It comes with practice. At lower magnifications you can handhold at higher levels on leaves in bushes etc.
The other thing to remember for best results is not to stop down all the way. Although your depth of field may suffer slightly by opening up, sharpness suffers quite badly by stopping down, especially at higher magnifications. I use f/8-f/11 at 1X, opening to f/5.6-f/7.1 at 4X or 5X. I noticed an immediate sharpness improvement compared to f/16.
Mark.