1. First and foremost, if you are a person that doesn’t tip or — whatever this is supposed to mean — doesn’t “believe” in tipping (as though it were a figure in Greek mythology), you are not allowed to go to restaurants. You cannot afford to eat out, either financially or ethically, or both. Spare restaurant staff your presence.
2. Research exactly how much servers are paid in your state, and adjust your perception of the job accordingly. If you are still patronizing restaurants believing that these workers make minimum wage (and compare them to fast food workers who are actually making that amount, even though that is its own can of worms), you are never going to be a decent tipper.
3. Ask yourself “Do I think that the person taking care of me through my meal and making my experience a positive one deserves to earn a living wage?” Examine that answer.
4. Personally speaking, I never tip less than 20 percent, unless the service is really bad. But even if you are a stingy tipper, going beneath 15 percent for good service is seen as a sign of disrespect. This cuts into the amount of money they will be able to pay their bills with, and it has little to do with the server being “greedy.”
5. Stiffing people is completely unacceptable. If the service is really that egregious, ask to speak to their manager and give some kind of real feedback instead of just leaving them with no money and no idea as to what they did. If there is a real problem with personnel, you owe it to the management to handle that.
6. If you are stiffing just because you are cheap, the wait staff should be able to follow you out to the parking lot and stab you.
7. Never take out a problem in your meal that had nothing to do with your server on your server’s pay. If a dish comes out not to your liking, but the server handles it gracefully, that is an issue you can take up with the manager or the chef. Don’t punish the innocent party by taking money away from them.
8. Understand that sometimes servers have to pay for the food that is sent back for frivolous reasons. This shouldn’t prevent you from doing it, but it should make you more judicious about what you expect to be comped.
9. Never base your server’s tip on what you expect them to have comped for you. Servers usually can’t go around giving free things, or adding on extras, and you shouldn’t factor that in to the kind of pay they deserve.
10. If you have hurled verbal abuse onto your server for whatever reason, this should be reflected in your tip. As a woman who has been called “sweetie” by a patron who then left me a ten percent tip, I can confirm that this is just about the most evil thing you can do.
11. If you are going to leave a coward’s tip, don’t run out of the restaurant to avoid eye contact with the server. Own your shittiness.
12. When you are in a big group, find some efficient way to organize amongst yourselves to leave an appropriate tip. A lot of time you all end up just leaving a dollar, and if the restaurant doesn’t add tip for larger parties (although this honestly happens when there are more than three people), there is almost no way to have quality control.
13. Leaving crumpled up bills that are all dirty or wet is just really insulting. At least smooth them out.
14. If you are going to hog a table for way more than is appropriate, and therefore prevent your server from getting some lucrative turnover, your tip had better reflect that.
15. Passive-aggressive notes left with shitty tips are the worst. The absolute, unquestionable worst.
16. If you have legitimate issues with the way state and federal lawmakers have handled food service pay, and think it’s both unfair and detrimental to the employees to put the burden of a server’s living wage on the patron, that is understandable. A lot of servers feel this way, too, even as they are living off of your generosity. But the way to exercise this belief is not in stiffing your waiters, or making a stand by leaving five percent on your checks. It’s not by punishing the people who already suffer most in this equation. You can choose to patronize places that pay their workers a living wage. You can write your congressmen, or participate in picket lines, or even open your own restaurant. But keeping food out of a server’s mouth in the name of personal politics is the worst thing you can do, and it just makes you an asshole. I would be sorry, but it’s happened to me multiple times, so I really can’t be bothered to sympathize with your morally pure view of the food service industry. 
