Hi annielaurie, I think that when looking for a design or dev agency, you need to have a solid grasp of product design. Various other aspects of design are also important such as information architecture, interaction design and visual design, but the crucial thing is being able to take a potentially loose set of requirements and creating either a web, but does it in a smart or innovative way. Another thing that you should look for is experience beyond just design. A designer who's also an expert front-end developer should have an understanding of what it takes to work on the presentation layer of a project. In my personal experience, I found this site http://faststartup.co.uk/ when I was also looking for services for my website. They specialize in responsive website design where your web page can look good on all devices. If you have time, try to check it out. :)
