It never really travels in a straight line. It is always going around the circumference of a circle.

"Should I be trying to keep my club going in a straight line?" And the answer is not. Do not "try" to manipulate the club or your swing path. You need to let the swing do it's thing. Proper fundamentals about the swing will take care of all that. It will naturally have a circular shape. If you try to change that, then you will be making minute adjustments that will cause great inconsistancies in your swing.