Recommendations

Many would choose on the basis of recommendations from a friend or associate. This is certainly an understandable sentiment, and it is because a webdesigner has many things in common with other fiduciary services like accountants, solicitors and so on. You will probably want to work closely together with the designer and he/she needs to understand your business goals and how to achieve them.

Portfolio

What earlier work can the web designer show? This is obviously an important criteria. If the portfolio is small, you have a case for getting a lower price.

Time in business

Be sure the web design agency is not some amateur who's here today and gone tomorrow. What is the history of the company, how many years have they been trading for?

Transparency

Deal with companies who are able to tell you upfront what is going to be involved and is willing to work for a fixed price.

Gurarantee

Do they offer any form of money-back guarantee?

Availability

Will the person or company be available when you need it?

Honesty and integrity

The web design agency should provide solutions that fits you, not their own pockets. They should have your interests in mind at all times.

How is their own website?

Far too many designers neglect their own website. If they have so little pride or interest in their own website, why should you trust them with yours?