Now, here's my little secret - I'm no designer. That's for sure. If I'm asked to design something you're almost certainly going to get a look and feel thats.... well, we'll be generous and say "safe." Given a mood board or other work of a designer, I can iterate and come up with something cool, but the fundamentals are definitely designer territory, not Catherine territory.
The difficulty comes when I have to hire a designer. Hiring an engineer is easy: I know what to look for; I know what makes someone effective or ineffective; and I can look at a small sample of someone's work and extrapolate. Hiring a designer is a somewhat more difficult proposition. Over the years, though, I've developed a pretty good idea of what makes a good designer.
I think of design as being broken down into two parts, aesthetics and reasoning. Aesthetic is the designer's "style." Reasoning is how the designer intellectually approaches the problem.
This is one design aesthetic (thanks to http://www.jessewillmon.com/):
This is a very different design aesthetic (thanks to http://www.mariusroosendaal.com/):
These are both portfolio pages - accomplishing the same purpose - but with very different aesthetics. The first is casual and friendly, while the second is much more corporate.
In my experience, most designers work with one or two aesthetics comfortably. When hiring for a designer, choose one who's aesthetic matches your own; those designs will be much better for you than if you're asking the designer to work in an uncomfortable way outside their aesthetic. If you're corporate, choose a designer with a clean corporate aesthetic. If you're going for an urban vibe (let's say you're starting the next great urban shoe craze), then choose a designer with an urban aesthetic.
But really, most designers have an aesthetic. They have a style.
What makes a good designer?
A good designer can analyze problems and analyze designs, and can explain the reasons behind the design. For most poor designers, the reasons behind the designs come down to, "Well, it just looks right. Trust me." A good designer will be able to explain the design decisions clearly, pointing out things like:
- eye tracking, including how the user will get information and in what order
- mouse movement and target size
- use of white space for clarity or emphasis
- inclusion of corporate branding elements
- conformance to or knowing deviation from similar problem spaces, either within the company or competitors
- the overall priority of the design (for example, guidance or creating excitement or accomplishing known workflows quickly)
- how the design scales up or down across the various target interfaces
So when I'm hiring a designer, I'm looking for only two things: an aesthetic that matches that of my client; and the ability to reason. Simple, right?