My first sortie with it, I managed to kill a Panther.
Use your speed to dart between trees, come in at an angle to your target. Start a circle and slowly tighten it but keep your speed up. Once you're close enough, start firing, preferably at their rear/tracks. Most tanks can't turn their turret fast enough.
Your real weaknesses are M8s, and a smart/accurate guy.
To counter the circle of death by M18s, don't try to "catch" him with your gun. Keep it in one spot, if he keeps going in circles, wait till he crosses your LoF and watch the fireworks. If he tries to outsmart you and go the opposite way, that's when you start tracking him, because any sudden turn he makes causes him to lose speed, which slows him down enough for your gun to "catch" him.
HE shells work best, because even a indirect hit will result in a kill.