Don’t overdo it. You may be in love with the hello kitty cursor or the flashy rainbow marquee, but for a person navigating your site for any length of time those extra “bling bling” over the top touches can be very irritating. In addition, they add to the time it takes your page to load and a user with a slow connection or substandard computer may decide to skip your site entirely.
Navigation is more important than pretty colors and effects

The very first thing to think about when designing your own web site is whether or not an average user can find what they are looking for quickly. People are impatient; never sacrifice ease of navigation for a pretty look.

Sound should always be optional

There is nothing more annoying than being blasted with sound when trying to peacefully navigate the web. Even soft background music can be annoying if the page requires an extended visit or needs to be refreshed frequently. If you insist on putting sound on your page give the user the option to turn it off.

Symmetry is not always pretty

This is especially true for text. Avoid centering large amounts of text. Making graphics or layout symmetrical can sometimes have its advantages, but when over used your website will start to look as if it was made by a ten year old with a cookie cutter.

Be careful with your fonts

Fancy fonts can look pretty in small doses, but make sure they are readable. Never use a highly stylized font in the body of your page. Also make sure to choose fonts based on your content. Avoid Comic Sans at all costs. Though most users enjoy comic sans, it looks very unprofessional to a designer. This font is disproportional and loose. It can sometimes be used to market to children, but even then a little effort will produce a better child friendly font. Also be aware that custom fonts will not show up on another user’s screen unless they are embedded.

Use Caps, Bolded, and Underlined text sparingly

If you have a large amount of items you feel need emphasis, use italics instead; they are much easier on the eye. Things typed in bold of underlined should be a rarity. All caps text should be avoided as well, even in titles. The less defined shape of the characters make the meaning of words typed in caps much harder to grasp at first sight.

Choose 2 colors, and 2 fonts maximum

An array of dazzling colors and fonts throughout your site may look good when viewing only one section, but a person visiting your site will be looking at the whole and getting a first impression that way. As a rule of thumb use no more than two different fonts, and two different colors of text on any one page.

Don’t allow your background to impede the readability of your site

If you are using a background image make sure it is washed out enough to not be distracting. Make sure all your text is readable on the color background you choose, even to those who do not have perfect vision. Just because you can read yellow on orange does not mean your mother or grandmother will be able to. Keep the visually impaired in mind when choosing colors and font sizes.

Don’t force the user to open a new window

This can turn into a cascade of windows that slow the user’s computer to a crawl. Only have pages open in a new window if the new window if a form or document that the user needs to save or print.

Provide proof of credibility

Give the user information to contact you with questions and cite information taken from other sources to make it easy for someone to use the information on your website in a professional environment.

Check your links before finalizing

After you do check every link in your site to make sure it works, recheck them. A dead end link is very frustrating.

Check your website on other operating systems

Your website may look marvelous on a PC using windows, but will it still look good on a Mac? How about on a Linux computer? To make your page accessible to a wide audience try to check your work on different operating systems, and also on computers with a smaller or larger screen size than your own. This will ensure that you do not lose potential viewers due to selective formatting.

Always spell check

But you knew that. Be careful not to use to much slang as well, or you are limiting your audience drastically. As said by experts from top web development companies, you content is king.