Answer: Know your purpose. State it in a single sentence. Your Web site's purpose might be, for example, "to sell our line of products." A good purpose will be specific and represent a new activity that adds significant value to the Web. Then state specific, measurable objectives that the site should accomplish.
Answer: A lack of understanding of the audience for the Web site. Understanding your audience means knowing their needs and expectations--what they do know, what they don't know. For example, a common error is when some sites that depend on an in-person visit (such as the Web site of a restaurant, festival, or real-world store) neglect to identify the city and state in which the store or physical event is located. The developers forget that the Web site is global.
Another common audience error is to assume that they know about the navigation cues on a site. Having symbols, links on certain words, and modes of representing the information based on clicking on links makes a site hard to navigate. The audience needs to be able to find out the navigation scheme of a site. Ideally, the scheme should be self-evident, even to a brand new user.
Answer: The way I look at it, Web development encompasses a whole set of processes, and one of those processes is Web design. Web design, unfortunately, has come to represent only page layout and graphics issues. I look at Web design as encompassing far more than that--including issues such as hypertext navigation, thematic issues that have to do with the Web's purpose, and organizational issues about the Web site's file organization. I hope people who call themselves "Web designers" understand this, but I think many do not.
Answer: No. Because a Web isn't just an object without a rhetorical or social context. Developing a Web site isn't just about screen layout, ergonomic optimization, choosing the right colors, and labeling links and buttons correctly. I see a total set of processes that include issues that one might call "project management"--planning, analysis, design, implementation, promotion, and innovation--but actually have to do with the ancient art of rhetoric and techniques of human communication.
Answer: Study human communication-- technical communication, writing, rhetoric, composition, computer-mediated communication, etc. Know how to identify an audience and shape communication in a variety of means (speech, text, multimedia) to deliver a message. Even advertising or public relations should be good fields for Web developers to study. Web developers should be aware of implementation issues, but unless you are going to be a specialist Web implementer, you don't need to study a lot of technical issues in depth. For Web implementers, of course, a thorough and extensive grounding in HTML, XML, and other standard technologies is a must. In other words, I think Web development has matured as a field to a point where there are specialties within it--technical, creative, managerial, etc.
Answer: Get some outside feedback. Developers are often not trained in human communication and make entirely too many assumptions about what an audience knows about the site's content or navigation cues. Feedback from experts in communication should help you. Definitely feedback from the audience can help--but you have to understand that excellent communication is usually structured intelligently. The structure shouldn't necessarily be run by a poll or a popular vote, or based on audience members who may have a very incorrect idea about what the site is all about.
Answer: Those that unabashedly focus on their purpose and have a strong sense of their audience. Yahoo.com's full coverage news area is absolutely fantastic--it accomplishes a specific purpose using the unique qualities of the Web; it has a clean layout and organization.
Answer: If you have a project that one person can do in their head, that is fine--no need for cooperation, a team, or even a process approach. But in general, most professional Web developers are in situations where projects are big and success needs to be reliable. I think a person with no training and no cooperation with others could produce a fantastic Web site. But I think Web developers can be trained to do a better job more reliably with a documented, process approach in which tasks and products of those tasks are systematically identified.
Answer: You can be master of your own domain! In fact, I recommend it. My costs for december.com have been: approximately $125 for initial setup and then an ongoing cost of approximately $10 per month and $50 per year.
Check out resources from the InterNIC or use the Alldomains.com commercial services for the procedures in your region for getting your own domain name. Of course, a domain name is just one cost of doing business. There are other administrative and technical costs involved.