Here are the principles of design and examples of each. Please feel free to use this as a reference.
Balance is the weighted relationship between the visual elements.
Composition is the organization of the elements of design into a unified whole.
Emphasis or Dominance
Emphasis is the focus of attention in a composition.
Harmony is the unity of all the visual elements in a composition.
Proportion is the ratio of one part of the composition to another.
Repetition is the use of an element or elements more than one time in a single composition.
Rhythm is the repetition of an element to achieve movement in a composition.
Unity is the organization of elements and principles into a whole.
Variety is the differences among and between elements in a composition.
Contrast where there is distinguishable difference between objects. This may be in shape such as the letter “s” and the letter “l”. Or it may be in contrast in tone, colour, mass etc.
Economy is the intentional removal of elaboration. Only the elements that have a purpose remain.
You can witness economy being practised in an advert when the product is the only item shown, with a very minimal (or plain) background.
Don’t offer more than is needed, but be sure to include all that is needed to create an intelligent and economical design.