Very simple technique and it will so improve your confidence, style and speed, not to mention accuracy!
Track the angle you wish to draw with your eye whilst moving your pencil on the paper in the same direction and at the same speed.
Check the angle of your line by laying the pencil on it, then without twisting the pencil, shut one eye to remove focusing problems, and hold it up to the angle of the object you are drawing. If your line is a bit out, you are then in a good position to fix it.
Go on, you know it makes sense ;)