The key is knowing how to identify those mistakes and fix them before they cause too much damage to both traffic levels and the general impression left by the site.
Common Mistakes
Made by otherwise excellent website designers.Not Suitable For Mobile Devices
1) Is your website a beauty on the computer screen? Not only does your website need to function on a smart phone or a tablet computer, it needs to look just as good on a smaller mobile screen as it does on the computer screen.
Spelling And Grammar Mistakes
2) If you want to completely decimate your professional image, all you need to do is misspell a word or two. But if you like making a good impression, you'll need to proofread your content multiple times.
Forgetting Social Media
3) If you fail to link to Facebook or twitter you're missing an amazing opportunity to connect with your website's visitors. Currently, Facebook boasts 1.06 billion active monthly users. Don't let them slip through your fingers.
Lack Of Site Map
4) There's no better way to frustrate website users than to make navigation difficult. Include a site map so that all visitors know where to access the information they need.
Not Testing Before Publishing
5) It's easy to make stupid mistakes in web code, but unfortunately, such mistakes can prevent your page from attaining accessibility. Test before you publish-- this will help you catch mistakes before going live.
Keyword Stuffing
6) It's tempting to stuff your page with keyword phrases, resist at all costs!. Good keywords are valuable, they get you to that top-ranking link. Only 8 percent of those viewers will continue on the click the second link.
Non-Adaptive Images
7) Adaptive images are effective in cleaning up messy HTML. Better yet, they work well with both mobile and traditional computer.
Flash
blog.incion.com/infographics/WebDesign/website-mistakes-done-even-by-good-web-designers