If a club is asking this question, it's (its leadership is) in serious trouble. The idea that somehow the "gentlemen" approach is the answer is not realistic. We throw the term around, yet we (editorial) tolerate board members and their wives who talk on their cell phones in the main dining room during lunch (contrary to club rules). We're a "golf club," not a country club, yet we admit members who don't know the basics of player and course etiquette. We admit as members people we think we'd like to have around, as members. We like them personally and enjoy their company. Why suspend them? Aren't we hurting ourselves in the process?
So what do we do now? I'm on the "education-is-the-answer" side. The difficulty is in pulling it off. Web videos on divot and ball mark repair? Won't work for those who don't look at them. I play often with a very good friend who thinks he knows how to repair ball marks, but he doesn't. He uses his ball mark repair tool like a roto-tiller. When I can, I try to get to his ball mark first and fix it for him -- not a good solution. I wrestle with how I can educate him to do it right without offending him. Any ideas?
What about mandatory education programs for new members? No golf until they've had an on-course class or two with the greenkeeper on the fundamentals, for the club, of divot, bunker and ball mark repair. What about required refresher courses every few years for existing members, conducted in a nonjudgmental manner? Singling out members for suspensions or fines is much more difficult than simply "educating" everyone. Sort of like renewing your driver's license every few years. Player etiquette, speed of play, etc. issues could be covered in a similar manner by the club's professional. Think about the golfers who pay the pro for lessons on their swings, and their putting and chipping? How many have paid for lessons on ball mark repair, divot repair and bunker raking (personally, I'm of the toss-away-the-rake persuasion, but that's not realistic)? How many pay for lessons on being a good golf partner, opponent or simply playing companion? Maybe we need to simply give those lessons away, and require that the gifts be accepted.