People go to resturaunts for many reasons. Ultimately it is with the idea to be served good food, in a timely fashion. 

You choose your restaurant with the cuisine being served, cost and level of interaction with the staff in mind.

Expectation of eatery levels:

Fast food, deli, diner, Casual Dining, Midrange dining to fine dining. Each of these have levels of food prep service and server attention that is expected.

Fast food: easy prep  limited range of foods offered,  bag it or tray.  maybe someone sweeping up the dining room and wiping tables.

Deli:   food prep  is higher level of cuisine. but still mostly takeout.

Diner :   more food prep,  seated,  coffee + meal  in-out goodbye. Maybe a flirty peppy server.

Casual dining:   something from the bar, appetizer and depending on timing, traffic and popularity of the location, there may be a wait before you can get your meal order in.

Tip:  To insure Prompt service.   Servers  work on a reduced salary, so tips are essential.The tips  will make or break  the budget for a waiter or waitress.  Knowing this I walk into the resturaunt with  the expectation  tip starts at 25%  and could go up or down from there.

This is where  the server makes or breaks their tip.   At least with me.   Server personality either augments, or detracts from the experience. 

Timing, attentiveness, attention to detail and a sense of urgency is vital

  It is the little things that make the experience what it is.

Servers:

Know your menu.

Be able to answer if it has ingredient "x"  in it or on it and whether it can be deleted.  Then make sure it has been deleted <made without item x> before you bring it to the table.

Cold food?  Don't bring it. 

Wrong order-  If you do not have the time to do it right the first time, when will you have time to do it over?

Attention to detail: If you are asked for  changes or different sides.  Make sure it is right before you bring it to the table. 

By now you are thinking  Duh!!   but  It does happen.

So now We  have a mistake made..........

Servers   "I'm Sorry."   Said  immediatly  and followed with  quick earnest attempts to correct the wrong action,  limited  excuses,  and if needed  managerial intervention  improve chances of  retaining some measure of the tip.

I have been known to give 2 cents  <two pennies>  prominently placed on the napkin stacking all plates to the side  so they cannot miss it.  Followed by  getting the manager to come outside for a chat.  

One Stellar Perfomance stands out........ 

Dennis  server at the counter  of the  Denny's   across the street from Disneyland Anaheim California.

6am  at the counter   August 2, 1981.

This guy  I swear had rollerskates on.  Constantly moving   hands full   whether it was menu silverware rolls    sweetrolls  or  coffee pot  always moving  always  talking  eye contact with everyone.   This guy  got a 50% tip.    food right  hot  fast  attentive  !!

Many servers think they just have to take orders and deliver food, but the role of a server is more important. Your customers expect you to know enough about the food and beverage menus to help them decide on their meals. They also expect you to be a good problem solver in case something goes wrong.

But your customers have come for the specific reason of having fun and enjoying a meal. They want to sit down, relax and enjoy each other's company, whether it's a date, business meeting or family dinner. Your customers can tell if you enjoy your job or are just plastering a smile on your face. To be successful as a server, you have to enjoy meeting new people and care about them as more than just a paycheck.

Be confident, and treat your customers as if they were your friends. Be courteous, and treat them age appropriately, of course.

They want to know which vegetables have meat by-products in them. Is the butter real butter or margarine? These may seem ridiculous things, but due to allergies and other medical conditions, some of your customers need to trust your knowledge of the restaurant you work in. They also want you to have the answers when they ask, and not have to run back to the kitchen every five minutes to double-check on something. But if that is what it takes paste on your happy face and do it. Offer if there is any thing else, while you are at it.

Timing is also important. Show some sense of urgency; Their perception is what drives them to creak open that wallet for the tip. Don' t stop at the side station for a chat when you are supposed to be getting the order in.

If a patron, not at your station or area, asks for the manager, don't run to their server and walk out with them. Go. Get. The. Manager!

Single diners are  a tricky breed.  Some want to order and be left alone, to deal with thier  blackberry,  notepad,  or  Book of choice.   Best to be prompt  attentive   and for gosh sakes  keep thier  glass full.  Keep the  "is everything ok ??  "  inquiries to a minimum,  if something is wrong  you will be told for sure.

Some others  think you are the font of local color  or  really want to chat it up. 

There is  no need for you to be invested in the chat  but you can be friendly and busy....