The only thing you can do is change the Smoothness in the Properties box.Less smoothing gives you more control but it also tends to make the line wiggle more unless you're zoomed in really close to it. You might also want to update your Wacom driver (if that's what you're using)
Can you describe the exact traits you're hoping to achieve? I would suggest toggling Pressure sensitivity on the brush tool. Turning it off will give you a steady thickness, while with sensitivity on the stroke will become thinner as you release pressure.