There are actually FOUR completely different skill sets needed to build a good, effective website.

1. Computer Programming.
2. Graphic Design.
3. Marketing Know-How.
4. Internet Marketing.

Without all four, your website will be at best a partial success. Let me explain:
First, a website is really a sort-of computer program, so your website designer needs to know the technical aspects of making sure your website functions correctly. These days, that is less of a problem than it once was. Way back in the ancient Internet days around 1997, someone had to be an expert computer programmer to produce a website. Of course, since expert computer programmers are rarely good artists, that made for some really ugly websites, some of which are still around.
These days “authoring tools” handle most of the technical aspects. One way to tell if you have a professional web designer is, does he use professional web design tools? Probably over 90% of all professionals use a program called Dreamweaver.
Even with Dreamweaver, someone ignorant of the technical aspects of the web and web design, can easily turn out a technically incompetent website. For example, it isn’t difficult to produce a website that is invisible to search engines – depending on how it is built. Meanwhile, a site that looks identical might be very search engine friendly.
The second vital talent is graphic design. A website should look good – it should even be a work of art in and of itself, that makes a visitor go “ooh” and “ah”. That artistic appeal is a function of the designer’s artistic sense and training and his skill in using the modern day tools of graphic design – highly complex and sophisticated programs such as Photoshop. Most professional web designers started out as graphic artists.
Unfortunately, far from all graphic artists are competent in the technical aspects. Every web designer claims to be an expert in search engine optimization (SEO). Few actually are, with many designers knowing only a few things about how to build a site for optimum SEO – and those often wrong or out-of-date. There’s lots of bad information out there.
The third piece of know-how is the one most designers are weakest in: Marketing. Websites usually have a marketing purpose – to sell a potential buyer, to create interest in your product or service, to build trust to a point where someone will pick up the phone. Confusing navigation, poorly written home page copy – there are many ways to waste your visitors. If marketing skill isn’t applied to the creation of a website, at best you end up with a pretty site that works properly – but doesn’t make the phone ring.
And that puts them in the same category as all the memorable, award-winning TV commercials that never sold a single car, beer or got someone to go see a movie. The fact that giant corporations can waste millions of marketing dollars isn’t much of a consolation when you find your website isn’t bringing in the customers. At least if you are a General Motors you know the US Government won’t let you go bankrupt without bailing you out (or maybe it will….).
Finally, when you have a great site, you still have to drive traffic to it. For most sites, that takes expert Internet marketing, which includes SEO (Search Engine Optimization) as the most important aspect, but also can include “click ads” (paid ads on Google and the like), publicity, etc. It can be summarized under the term “Internet Presence.” In short, if someone is looking for you, or someone like you, how likely are they to find your website?
Your best guarantee of a successful website is making sure that whoever and however they are supplied, that all four of these areas of know-how are well executed.
These days, every business needs a successful website.