A trick ive been practicing with him is bouncing grenades off the ground into people instead of a direct shot. Ive noticed that if you aim at the ground and bounce them, if you miss, they land closer to the fight and also explode on their bounce timer more quickly. Also greatly helps for sending them under a payload and other odd situations where aiming direct may be more difficult.
Another dirty trick takes confidence to pull off, but its throwing the mine the exact moment you take a shot that you know 100% will land. The mine and the grenade will hit at the same time and that burst leaves no time for reaction from the target, and works great on enemy healers.