Site contains typographical errors
Typo's, spelling and grammatical errors on your site can all lead to a visitor's impression that your company offers an amateur approach.
Just spending a few minutes re-reading each page's copy can help prevent this. Better still ask someone else to read it without having seen it before. They will be extremely quick to point out errors.
Failing to highlight the benefits of your services
People want your products or services to help them in some way - either from the pleasure of buying the product online OR from knowing the supplied service will help alleviate a (potential) problem or make their life more comfortable.
No calls to action
Your visitors MUST be told what to do! You must carefully think what kind of call to action you will need - and it's position on your page to generate a sale or lead.
Don't tell someone what to do and they will move to a site that will tell them!
Carefully weigh up the length of website pages against the amount of useful tips and information.
Try to keep your readers interested by using white space, words or sentenced in bold and links within the text
Avoid long tedious sentences as that can send users off to another website.
It is a fair balance between enough content on the page for search engines to index AND generating interest from your site visitors in what you have written.
Include Copyright statements
Every page should include your copyright statement. Unlikely to send visitors off but it may lead some to think if the design and content you provide is not from your own efforts.
Lack of Privacy Statement/Policy
If you do not clearly state what you will do with a potential client's email or telephone address on your website how will they know you are not going to pass it to all and sundry?
Do your visitors a favour and let them know you will be the only one to use their email address - AND make sure you stick to it!
Visitor or Hit Counters
Your visitors are not interested in the number of hits your site has received. If they see a figure that is high they tend to disbelieve it and if it is too low they will feel your site is unsuccessful. I recommend you avoid the use of counters on your website.
Under construction signs
If your site is under construction do not tell people it is ready to be viewed. "Under construction" signs are a display of a website built by beginners/amateurs who may be struggling.
If possible comment out the code that links to your under construction pages and until you are completely ready do not show your site publicly.
Under construction signs are possibly the most common mistake by business website owners keen to get their company online.
Design By Committee
Though teamwork is essential to the success of a website, requiring group consensus for decision making can stop a project in its tracks.
Text As Images
Typography within a web page can be a bit limited which leads to a common problem: namely presenting text as pictures. So if you want to have nice looking text there is a temptation to have the text replaced by an image of that text. However, search engines can’t read the text when it is presented in this way.
Frames are a way of wrapping up some web content within a web page. Essentially a page is hidden inside another page. There are a couple of big problems here. Firstly, there isn’t a way to bookmark where you are inside a frame. Secondly, because many search engines don’t look inside frames they effectively hide your content.