It is not sufficient, for instance, for the firm to simply grant the designer a free hand. When it comes to industrial design, nothing is accomplished merely by an unstinting generosity on the part of management–the kind of profligate benevolence often practised by American firms. Rather than providing a blank check, a firm needs capable workers in its various departments, dedicated people with competence and experience, and it needs resources of many kinds–if good design is to be achieved and actually implemented. – Dieter Rams
Recently, I’ve come across a few blog posts which appear to emphasize designers as a factor of startup success. As with most things on the web, it is important that one approach such material with a slight sprinkle of skepticism. Articles such as these show a rush to hire designers as a means of tipping the odds in favour of one’s startup’s success. However, one must wonder how true these claims are when one considers the number of successful web companies with a founding team consisting solely of engineers.
The only designer co-founder you would want is one who is also technically competent to an extent, as the odds that you will be pushing the envelope of the person’s comfort zone are pretty high. If the choice you have is between a pixel-pusher or a programmer who dabbles in design, the best call is to go with the latter.
Note: if you are an engineer and you are at the point where you wish to get better at visual design, read a book. Heck, read two. Now, you know more than enough to cope with most decisions you will encounter. The capability to build a product and evolve its design from feedback is more important that having a “trained and skilled designer” in your team from the onset.
If/when you do decide to find a designer
In my experience, it is remarkably difficult to judge the capabilities of a designer based on portfolio services such as Dribbble and Forrst (what most people seem to recommend). This is because they tend to focus on aesthetic value rather than problem-solving skills. Even with services which were initially designed to show work-in-progress, they quickly converge into a gallery as users realize that the easiest way to gain popularity is to show finished work that is positioned in the best light they can muster (after all, who doesn’t want to be liked by many?). One can only barely glean what a designer knows from a few screenshots. You need to know how much of the actual interaction was designed by the person and how well the proposed solutions (which is all they are) work in practice. Perhaps it would be interesting to have a gallery where the portfolio pieces also communicate how they work in practice – a “design-fiddle”, so to speak.
Aside: If you are a “designer” that is unaware of the medium you are designing for and incapable of at least building a prototype, you are a dreamer and should market yourself as such. There is no shame in that.
Build a business
Rather than granting designers full control over the product, remember that they need to play nice and integrate with several other aspects of your business.
You need to remember that you are building a business not a pretty app. A designer co-founder could help (as could a sales co-founder), but does not offer any guarantees that you will make good business decisions, regardless of how “beautiful” an experience your application offers (not to say that adding more engineers does). Visual aesthetics are rarely enough. Getting a product into the hands of potential customers is important.
I am concerned that “I am looking for a design co-founder” will become the new “I am looking for a technical co-founder.” We need to make more useful software. Quit stalling. Learn what you need to get things done.
De omnibus dubitandum. – René Descartes
If a reader is aware of a study that quantifies the influence of “good” design (however that is defined) on startup success, I would be interested in having a read. As far as I am aware, there are none.
Judging from the comments on Hacker News, a point I do not seem to be communicating effectively is that hiring for design is terribly broken. You can work out, to a certain extent, how people reason by reading their code but you cannot do the same by looking at their design portfolio or gallery. This needs to change. While it worked reasonably well in the advertising agency days, it is becoming increasingly useless for this decade. Mea culpa.
 Dormer, P., 1993. Design Since 1945, Thames and Hudson.