There are many websites on the internet which have great designs, are easy to navigate and have quality content. But, there are far more websites which have none or few of the characteristics which make a website "good."
Sometimes websites are designed by an inexperienced designer, who thinks design is about pretty colours, mind-blowing high-resolution graphics and "fantastic" animations on navigation buttons. Other times, they are designed by non-designers (ie web programmers) who think it is about the content.

www.thisisenglandmovie.co.uk - The Y Design Awards' 2007 Best Online Campaign
A good web designer will understand the importance of getting the correct balance between aesthetic elements and the actual content (the stuff the visitor wants: an article in case of a blog).
What the visitor wants: the content
Most first time web designers make the mistake of thinking that visitors come to websites to look at the visual features; and, that's what they design the website for - to be looked at.
But, take in consideration what you go to most websites for. Usually, it's for the content - that is why you're reading this article rather than looking around for something to catch your attention (hopefully).
So, it's important that web designers base a website around its content and purpose. But, it's also important to get the balance right: if they ended up creating a just textual document, it would be bland and boring. It would also cause a problem with how the visitor navigates the site.
The balance between aesthetical elements and useful elements depends on the type of website: a photograph website may need to be biased towards aesthetical; a blog needs to be biased towards being useful (having useful content and articles).
Ease of navigation
Visitors can get to your website with relative ease. But, if it's not designed well, they may not be able to get around very easily.
The first thing you must ensure is that all your navigational elements are grouped together and are easily identifiable. If they aren't, visitors will not even know how to navigate your site, let alone actually get from page to page. Importantly, do not blend the navigation in with the surroundings too much, and do not break up the navigation section with non-navigational elements, such as advertisements. (See: The Benefits of Having Two Sidebars).
Secondly, you must ensure that you provide the visitor with enough tools to allow them to get to the content they want. It is too often that I see websites just using a navigation section with 5 buttons or so - sure, they get me to the "main" pages, but, what if I wanted to get somewhere else?
Oppositely, too many navigational elements can make the navigation slow for a visitor. For a website with many navigational elements, you may want to consider categorising the elements (sidebars on blogs often do this).
And, thirdly, good websites should also offer alternative ways to navigate them. Examples include in-content, or in-article linking where appropriate, and including a sitemap for sites with many pages. For sites which have pages in a hierarchical structure, it may be appropriate to use breadcrumbs.
Adding a search utility is generally a good idea, and many people like to use them (they are used to typing things into search engines and getting relevant results). Personally, though, I tend not to use search features on websites, unless I can't click my way through.
The content: how to present it
As I've said, websites should have content at their focus. But, it's important to understand how you should present the content, and how the visitors expect to see it. Formatting the content helps visitors understand the effect of text, and allows them to separate the text into different sections.
One of the most important things that can be done is making the content the most noticeable part of the page. This involves creating near-100% contrast between text and it's background: it's best to use black text on a white, or near-white background. It is equally important to eliminate any attention-stealing animations, graphics or other elements.
Another important thing that can be done is to use headings. Headings separate the text into different sections - like paragraphs, but at a lower scope. Headings should be descriptive of the paragraphs that follow - if you just read the headings of this article, you'd get a general idea of what it is about.
The use of images and diagrams can be used effectively on some pages. As long as they are relevant, I see it as a benefit to assist with the text as some people can understand something better with visual material.
A summary
Here's just a quick summary of the points I mentioned above:
- Get the balance between aesthetical and useful (content) elements correct;
- Group navigational elements together, and make sure they are noticeable and consistent;
- Make sure you have the right amount of navigational tools: not too few, nor too many;
- Add alternative navigation methods: search tool, sitemap, in-content linking;
- Use headings in text (especially long articles);
- Use images if appropriate; and,
- Make sure the content contrasts well, and is the most noticeable part of the page.

