Logo designers have several puzzles to solve when presented with a new logo design project. One of the main considerations that a designer must deal with is to understand what it is that the client wants to achieve with the logo design.
The designer asks the client a series of questions that illicit answers helping to bring the parts of the puzzle together. A typical question might be “What qualities does your business want to be known for?” The answer might be for a doctor for instance, “I want to be known as someone you can trust”. So the question and answer begs: How does the designer portray trust in the logo design?
Scientists have been studying the way we react to colors for many years. Certain colors make us feel a certain way about something. As long as the designer knows what these colors and emotions are, the designer can use that information to help present the business in the right way. These are not hard and fast rules but smart designers use the information to their clients advantage.
Source: http://thelogocompany.net