What to do when you invite someone round, how to set the table, how to arrange the seating. 
A few simple rules for you to remember. 

4	Seating positions at the Table

The hosts should try to sit opposite each other. 

Almost at the same time as the female host, the women should find and take their places

The guests should find 'seating labels' on the table, with their title and surname written out in full: "Mister Smith", "Doctor White". If, however, the guests are close friends, it is sufficient to write their first names. 

The female host should have the oldest or most important male guest to her right, and to her left the next oldest or most important. The male host should have the oldest or most important female guest to his right, and to his left the next oldest or most important. 

The other guests should alternate male-female, leaving the least important the furthest away from the hosts. Single people and family members should also be positioned furthest away. It is, however, obvious that you should not seat your mother-in-law or elderly relatives in the distant positions. 

For a successful lunch

In order to ensure a successful lunch, the female host should bear a few important things in mind:

a) Guests must be able to mix well amongst themselves. 
b) The menu should have been previously tested. 
c) Between one course and another, the breaks must not become 'empty spaces'
d) The waiter or waitress should not make mistakes, but should she err, she should not be reproached in any way, neither verbally nor with a stern gaze. 

In no case should the female host insist on a guest having a second serving of any part of the meal.