There are many mistakes that are commonly done that can literally make or break a business. It's best you learn from these mistakes and soar to the top of the major search engines around the web.
Google rewards unique fresh content and penalizes duplicate content. The best way to avoid duplicate content is to either write your own content, rewrite articles you have rights to, or outsource content from a professional writer. Avoid duplicate content by all means necessary. Duplicate content can make or break your business. Many people are at the top of the search engines one day and in the Google "sandbox" the next simply because of duplicate content.
Not Enough Keywords
Some webmasters make the mistake of not putting enough keywords on their webpage. If you are trying to run a successful business then it is important to put keywords throughout your whole article enough without keyword stuffing (putting too many keywords in the article). You can put keywords in your domain name url, in your H1 title tags, meta-tags, and throughout your whole article. Make sure you have highly targeted long-tail keywords in your article as well. One thing that you can do is read online testimonials at http://www.siliconbeachdigital.com/ to get brief account.
Trying to Trick Google
Google has been around for quite some time, and they have literally banned thousands of websites for trying things called Black Hat SEO. Black Hat Search Engine Optimization may work temporarily, but in the end Google will catch on to your tricks and eventually penalize or ban your website from their search directory. When your banned from Google, it marks the death of your website. Avoid Black-Hat techniques at all costs.