Serving a large number of people as quickly as possible takes planning. Since each person can easily take a minute in the line, for the fastest service, it is a good plan to have one service line for each 50-75 diners. This article outlines laying out the service lines for your buffet.
Before the Buffet; Why You May Need an Appetizer Table
A self-catered buffet is a real challenge to the organizers, and things don't always come together as smoothly as hoped. By planning and setting up an appetizer area or "nibble table" which is ready when the guests begin to arrive, the cooks and servers have time to complete the arrangement of the dinner buffet. This is especially critical if there are children among the guests, or there is a wait before dinner, as at a wedding reception.

This does not have to be complicated. Three items, including a fruit tray, a cheese tray and an attractive dip or spread, plus a punch, or two if one is alcoholic, are sufficient.

One appetizer service area is needed for each 100 guests.

Now,on to dinner:

Meats, need all:
Pork loin- 1 pound raw boneless per 3 people
Poached salmon- 1 pound fillet per 4 people
Grilled chicken- 2 ounces per person cooked= 3 ounces raw boneless or 1 small piece whole
When you offer several meat choices, people take more and many take some of each

Potato salad- 30 pounds potatoes per 100
Pasta salad (orzo)- 6 pounds dry pasta per 100

Green salad- see plan for 100 page

Fruit salad- strongly recommend you do fruit trays instead; keep better, easier to serve, and leftovers are more usable.

Mixed summer veggies- 22 pounds ready to eat per 100 (how much raw/as purchased depends on what veggies)