Tipping

I've never worked a job for tips but I can imagine the aggrivation that can come from it. Sure, as a Starbucks barista we got tips, but it wasn't a tip based job such as being a waiter, delivery runner or driver. Service is key. Presentation is important. You have to make your customer believe you care about their business. I'm sure the act gets tiring. Trying to please multiple tables of guests, giving each enough attention without being overbearing. And many times, it's customers you'll never see again, so you have one chance to impress them for a good tip.
But when it comes to becoming a regular at a place, I find tipping to be essential. You want that bartender to know your drink and give you priority over other customers? Tip him well. You want your pizza to arrive fresh hot out of the oven? Tip the driver well and he will make stops to your house first.
Generally, here's what I do. Bad service, minimal tip of 10-15%: give or take double the tax. Average service, round tax up to whole number, double it, and then add change to make bill's total into a whole number, which comes out to 16-20%. Great service, you will be rewarded nicely by 20+% tip. A lot of my friends look at me with displeasure when I leave the final tip, often pulling extra money from my own wallet. They say it's unneccessarry and I'm being overly generous. I get pissed off at my cheap friends who find it unnecesarry to tip devlivery drivers for Chinese or Pizza places that advertise "no delivery charge". Right. They're not charging for delivery, but you should tip the driver instead.
Service changes if you tip well. Tip well and be polite. In the end, they hook you up with priority, discounts, free desserts or appetizers, drinks on the house... And when you get hooked up with these extra goodies, it puts you in a better mood. And being in a better mood, makes you nicer to the server. It's a circle of niceness that benefits all parties.