First things first, from now on don't call the people you are serving customers ... call them guests.
Make your guests feel at home and welcome. I usually do this by verbally saying they are always here, but there are probably better ways.
With that said - you do have the right not to serve a customer if they are harassing you, drinking too much, didn't pay last time, etc.
Know the menu! For example: if all burgers come with a side of fries, ask them if they want fries or a substitute.
Know some drinks! If a customer asks for a mojito, it helps to know what a mojito is, if the bartender says she doesn't know how to make it ..
Bring cutlery and side plates before you bring the food. I try to bring them just after they order to make sure I don't forget .. because that can be embarrassing!
Management is going to want you to up-sell, so if it's dinner offer a dessert menu and coffee at the end.
With that said - don't ask them if they want anything else while they are waiting for their food.
If you have trouble remembering orders, it's okay to write them down.
Smile. I hate saying this because I hate being told to do it, but it helps you get better tips.
Look clean! Washed hair, washed finger nails, clean clothes, etc.
Makeup isn't mandatory but it can help sometimes. It can also be fun.
It is best to avoid perfume, some people are allergic to it.
If you think you might forget a task that you need to do in ten minutes, it's okay to write it down.
Check the order before bringing it to the table.
If there is a mistake don't blame the chef or anyone else. Just apologize and fix it.
Never complain about a bad tip. The only time you can mention a tip is if you are saying a simple thank you.
Never sit around doing nothing. 'If you have time to lean, you have time to clean.'
Stay neutral in arguments about who will pay.
Ask if they would like water when they order coffee or alcohol.
Bring extra cutlery for specific orders. If someone is getting a steak, grab a steak knife. If someone is getting a soup, bring a spoon. If someone is getting a coffee, put a spoon on the side.
Don't set dangerous objects near children. If the parents order hot soup just try to keep away from the kids a little.
If you don't have an apron pocket, you can consider buying one online.
Familiarize yourself with the daily specials. I hate to say this but it's best to do it before your shift even starts.
If someone is getting take-out, bring it in a plastic bag with plastic cutlery and napkins.
Don't let it get to you if the other waitresses are being mean to you, they could easily just be jealous you are getting better tips or they are just stressed.
Know the numbers of the tables, trust me it helps. Also it looks really bad if you don't know the numbers.
Choose the music with some care. Don't play a whole album of the same artist. In the morning, play softer music and in the afternoon, play more energetic music.
Perform unpleasant tasks without complaining.
Keep the music a little low so that guests can still talk to each other.
Want more tips? Good! Introduce yourself, make eye-contact and be friendly.
Befriend the regulars. Remember their names and favourite drinks. Make them feel like they are coming to visit a friend: you!
Don't gossip about customers, even if you think they can't hear you. Just don't risk it.
Show up to work early. This is important to any job, especially if you are new.