We found that it is sometimes not easy for buyers of design to make the right decisions. A number of questions that you might want to ask yourself are: Can you see that they have the full range of skills for your project, and have they used them successfully for other people? For example, will the production engineering be handled in-house or at the factory, or do you need the design company to handle it? Do you like the results of their past projects? 

Personality 

The product design process can be long, and involve much negotiation and compromise between several different parties. Choosing designers with too much ego, or with too little experience, can make it a frustrating experience. 

It makes sense to obtain several quotes, but you should carefully compare a detailed breakdown of the quotes you are given – different companies may be suggesting different amounts of work. There may be nothing wrong with this; product design is a complex process, and the most efficient and effective route through it should be discussed.If the success of your new product is a priority, and it warrants being visually and functionally sophisticated, then it would be prudent to invest in a comprehensive development program for it.

Preparation
First of all, gather as much relevant information as possible. In some ways, you are the best source of information because of your knowledge of your specific market; the more of this knowledge you can impart on the designer, the better informed the design will be.As much as possible, let the designer share the experience of your customers. Let them use your products, find out for themselves what is good and bad, and talk to existing users.