The most important thing to remember about dining out is that the server makes his/her money from the people dining. Therefore, regardless of the stories you have heard, your server will do his/her best to make you happy. Otherwise the result is less money. It is a very clear relationship. On the other hand, waiters are not actors and we shouldn't have to pretend to be your best friend to get an adequate gratuity.
Waiting tables requires more than taking an order, bringing the food and collecting money. A good server knows everything about the menu, all the beverages and can tell you how you can and can't change the menu. The waiter is your liaison between you and the kitchen, the bar and the host staff. They also time the food coming out of the kitchen and coordinate their busser/server assistant/back waiter. All this and a smile as well.
Also, I understand that most other people don't get tips and that it seems weird to people that they are obligated to pay even more than the bill for what they have purchased. However, restaurants are able to stay in business by paying their waiters, bartenders and bussers minimum wage or less. If you wanted the restaurant to start paying compensatory wages then the cost of dining out would be prohibitively expensive. Servers do more than take your order and bring your food and collect your money, we serve you, wait on you, essentially fill a job requirement that your own family might be loathe to do for you.
That having been said lets start the class.....
These days the Internal Revenue Service is much more watchful of the Hospitality Industry and everyone gets to declare their income. Based on credit card tracking they think that a server tends to take home around 10% of their sales, which is normally fairly correct. In the restaurant I work in, I tip to the other service staff 5 to 6% of my sales or higher. Therefore to even make as much as the government insists that I make, my tips have to average about 16%.
Most servers end up tipping out about 30% of their intake. I make sure to tip the Host Desk (.05% of sales), the Bartender (.05% of sales), my server assistant (normally around 5% of sales although it can go as low as 2%) and in other restaurants they also have to tip the person delivering food for them. This means I don't take home all the money the restaurant patron leaves, far from it! If a guest leaves me under 15% it actually costs me money to have waited on them since I have to declare at least 10% and I am tipping out around 6% or my sales.
If you received everything you asked for, in a timely manner and the server made sure to come back after you got your food to make sure everything tasted good and was cooked correctly, then the minimum you should leave is 15% of the TOTAL bill. Yes that includes the tax (I have to pay taxes to the government based oh my total sales including tax, maybe your state is different but that is how it is in my corner of the world).
Now if you got all of those things and the server made good suggestions, offered to get you more wine (or whatever you were drinking), kept your water/coffee/tea full then the tip percentage goes up.
If you actively LOVED your server and he/she enhanced your dining experience to the point that the service was even better than the food, more than 20% is called for.
A note, if you are dining with a coupon, or get something for free, then tip on what the total would have been if you weren't receiving a discount.
Sometimes 15-20% isn't enough. "When?" you ask. When you are getting a deal, using a coupon, dining or drinking during that horror known as happy hour. Just because the drinks and food cost less, that doesn't mean that the server works less hard.
This applies to when you are in a bar, especially during happy hour. Bartenders and cocktail servers have even harder jobs than waiters because they deal with people who are drinking. Also, they probably have a lot more people to wait on but because drinking tends to be less expensive than eating, especially during happy hour, the sales are a lot lower. This means they make a whole lot less money for a lot more grief.
If 4 people have 3 drinks each during happy hour and your bill is only $24 (yup that is $2 a drink, otherwise known as happy hour hell) then leaving 15% is not only not adequate, it is insulting. It makes sense to treat the bartender/cocktail waiter at your local really well because ,I assure you, they have good memories. Leave a bad tip after getting good service in a bar, you will find that upon your return you have suddenly become a non-entity. Simply because you have already proven that even with good service there won't be an adequate reward.
Now what about at your local coffee shop? Same thing applies.
As a guest leaves they stop and say to their waiter, "Thanks! That was a fabulous time, we really enjoyed ourselves. We are going to ask for you the next time we come in." Nine times of ten this means that the guest just left them 10% or less. Somehow the guest thinks that merely hearing about good service makes a waiter feel good. Wrong! Waiters love to hear they gave good service, however the clearest way to signal this is to leave a good tip. Remember, actions speak louder than words.
This is usually accompanied with a strange request or some really high maintenance table. The guest thinks that if they tell you they will leave you a large tip you will break the rules for them. The big kicker is, anyone who tells you they are leaving you a good tip is generally wrong. This means you are going to bust your ass for less than 10%.
Remember that this person is driving your vehicle worth more than what you are going to spend on meals for at least a month. $3-5 minimum, regardless of whether you were charged for parking your car or not.
Yes, you DO tip on the cost of the wine. I have to pay taxes on it and I have to suggest a proper wine to match your foods and then do the proper wine presentation at the table. Wine presentation can be a time consuming activity, commonly throwing off the timing of helping other guests. Don't get me wrong, I think the wine presentation is one of my favorite parts of the dining/waiting experience. However it isn't just throwing the bottle on the table and leaving you to your own devices. Tip accordingly.
If your busser/server assistant went out of their way to help you, side tipping is nice but it shouldn't lower the price of the tip you leave the server.
If you are in a situation that you are unsure of whether to tip, assess if you want to tip because someone helped you out and then do! It might make someone's day!