Since I play a lot of muni courses, and mostly on weekends and in the afternoons to take advantage of the twilight rates, the greens are usually pretty thrashed by the time I take on the course.
My question is: to what extent do the rules of golf allow me to repair the greens prior to putting? I assume I can fix pitch marks and remove loose impediments in my putting line (can I even do that?). How far can I go in ensuring that my putt doesn't fall offline by a man-made obstruction? Can I repair spike marks? What about huge tufts of grass?