Make sure all the text on your site is easy to read.
Avoid "busy" background images that draw the attention of the visitor away from the text.
Stick with plain backgrounds, follow the design of successful sites.
Be careful with color selection and saturation.
Do you want to keep visitors reading your site for any length of time?
Then don't use too much red, yellow or orange it's hard on the eyes.
Stay away from too many colors that will clash and compete with each other.
White backgrounds are used for sites with a lot of text content, while black backgrounds are usually used to achieve an effect of "coolness."
Choose only 3 or 4 main colors. Bland is better, The text is king
Don't require more than four clicks
on the scrollbar to get to the bottom of a page.
Create short pages with one topic per page. Each page is then formatted for the search engines
Tell visitors what your site is about
Make sure that your main page tells visitors what your site is about and has something to grab their attention. Otherwise they'll leave.
Always put contact information
on your site so that people can e-mail you with complaints, suggestions, and compliments.
Try to reply to all e-mail within 48 hours
Use a graphic for your email address, otherwise spammers will find you.
Make navigation on your site easy.
Have navigation links at the top, bottom, left or right side of the page. Keep the navigation consistent throughout the site.
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Make sure all the images on your site work
It gives your visitors a poor first impression if images don't load, and they will often leave.
Check and recheck your spelling
especially if you're trying to run a business over the Internet. Use a spell checker.
Having lots of mistakes makes your site look like it was made by an amateur
If you are selling something through your site, state it up front on your main page
Don't force people to go down 4 links before finding out that you are selling something.
Give a picture of the product.
Tell people why they need it. Assure them that their credit card is secure, and offer an address and phone number.
Keep your site consistent throughout.
Don't have a different background color on every page, or a different navigation scheme.
Try to have at least one small icon on every page on your site, somewhere at the top preferably, so that people will know they are still at your site.
The more often you update your site, the more visitors you will get.
Change your site at least once a week. You don't have to spend hours modifying the entire site -- just 10-15 min/day will do.
Content, content, and content
Your site can't be like everyone else's.
It should to be unique and provide interesting content that you can't find anywhere else.
Always promote your site
Visit sites that have a theme similar to yours; submit to search engines, swap links with other sites, add your emails, etc.
Once you stop promoting your site and updating it with fresh content, people will stop visiting.
Test your site with different browsers
and screen resolutions, and color settings.
Build your site to the lowest common denominator, and if you must have a page for the newest browser(s) then offer visitors to your site an alternative.
Make sure all the links on your webpage work.
There are very few things as annoying as "Error 404 file not found."
If your host allows create a custom error page. Then when you do make an error you don't lose visitors Click here to see mine