With so much misinformation over the Internet, and an immense lack of knowledge about how SEO really works, you could ends up using the wrong practices and getting your site banned from the search engines. Here are some of the top SEO mistakes that you should avoid:

1. Never use Flash for SEO: Flash sites may be attractive and eye-catching but the search engine won’t read or index the content on these sites. If you cannot avoid using Flash on your site but you still need the search engines to index your site, then you should offer an HTML version as well. The search engine spiders cannot read Flash content and can’t index it.
2. Don’t overdo it with the JavaScript: Search engine bots are not designed to read or understand JavaScript. So, if your website contains a couple of lines of JavaScript, then the chances are the bots will ignore these lines. So, make sure that the JavaScript is kept to a minimum. Instead, you could create an external JavaScript file in cases where it is unavoidable.
3. Never link your Site to other low quality websites: Link building is a very important aspect of SEO. Most search engines consider the number of links that link to your site consider this as an indication of your popularity and rank you accordingly. However, it is very important to consider the quality of the sites that link to you and vice versa. Linking your site to low quality websites will have an adverse effect on the credibility of your site.