This is what I do when out: breakfast - hardly ever go, but when I do it’s all out - brekkie and a Bloody, maybe even something else too. So, it’s special, and I tip 15%, rounding up, to be generous. Lunch is infrequent too, but again, is 15%. Dinner, typically 20%, but if the servers are extra helpful or good, I go up to 25-30%. Typically the higher tips happen when we establish a connection of sorts, or if they recommend other places to go to, for instance, when we might be traveling out of town, to a conference, or something.
If the food isn’t good, I never send it back, unless it’s burnt all over and completely inedible. I know this is a kitchen fault, and don’t hold it against the server. However, if the service is horrible, they have a bad attitude, or just don’t care, it gets dropped down to 15% or even 10% in the most egregious of circumstances.
The last one is hotels: sometimes, during a conference or vacation, we’re in a hotel for 3 - 7 days or so; it used to be that I’d always leave some money in the room for the housekeepers to find, even if we only spent a night there. These days, I make a point of handing them a generous tip up front. Self serving? Yes, I know, but when I treat people well, it all comes back, in the form of extra coffee, a sewing kit, or whatever. Furthermore, I try to get to know the people I’m very blessed to encounter! I learn a lot, and yes, we wind up talking about their culture, or food ways, music or whatever. I’m very enriched by these encounters.
Finally, and I’m not trying to make myself look good, but rather, I want to share - when I was in New Orleans in 2017, I got pretty sick, early on in the trip. Big Bummer! Can’t even tell you how disappointed I was! The dinners and shopping were all planned out, but no, I was marooned in the hotel! 
Long story short, knew I wouldn’t be able to shop for the normal souvenir t-shirts and stuff that my family and friends didn’t need anyway, so I gave my relatively small budget for that away! To street people, artists and musicians. Can’t tell you how liberating that felt, as well, it made me feel better, after a traumatic travel experience. I did end up at Tulane Medical Center ER in the middle of the night. Thank god it wasn’t a weekend! You can better believe I took care of everyone that took care of me. I’m talking about the wonderful people at the hotel, the cab drivers. etc. The hospital staff were great, but of course tipping not appropriate! 
I’m forever grateful for the kindness I experienced on that trip, it was truly humbling.
