I have a phone app where you put in the total and what % you want to tip ad it tells you... Or in calif I just double the sales tax and round up to the nearest dollar if I only want to do 15% (sales tax here is 7.25%
If I get good service, the tip will be close to 20%, these people work hard for their money. Poor food and product is not the servers fault, but inattention and bad service is. I also look at how a server handles a bad situation. Being self-employed I really am keyed into what service to the customer means. Personally I thrieve on repeat business, and as I get closer to retirement, I'm not looking for new clients, want to give quality service to my old ones. This is how I base the service of others, and the businesses they represent. In short, I reward good service.
Some of my kids are in the food service industry so I usually tip there at 20%+ maybe loose change. I usually don't wind up in places that require tipping. lol ...Frank