1. Avoiding creating responsive design.

This is the biggest mistake you are doing. Since over 40% of modern searches conduct on smart phones or tablets. Not having a mobile friendly design is actually irritation to the user. This results in distraction of the user from your website to any other way to get his desired products and services.
 

2. Too much Loading time

No one likes waiting. If your website is taking more than 3 seconds to be loaded, consider it as failed. Website load time can directly affect sales rates, search engine rankings and customer loyalty. Try to reduce the website loading time with optimizing images, removing unnecessary plug ins, use browser caching etc.
 

3. Bad Navigation

Making navigation menu hard to find is a common web design mistake. Bad navigation force user to quite your website. Make sure that the flow or navigation aspects of your website are easy to understand and even easier to find.
 

4. Poor use of contents and white spaces.

Contents tells readers everything about your business. Too much cluttered contents, spelling mistakes, uneven font sizes and type may discomfort user to read the text on your website. Use small sentences and simple languages. Break the text wherever you can. Make the good use of white spaces to bring the eye around your site.
 

5. Irrelevant photos and images.

Filling up the Web Pages with lots of images is not at all a good idea. Do not use generic images. Generic images leads users to the wrong directions. It makes something wired combinations when text contents and images are not matching with other. Use specific images which relates to that topic or section where they have been put.