Getting started with delay
In many organizations people may feel that SEO – is something like a selection of keywords and copywriting, but do not consider that SEO is also playing a key role in the technical implementation. The main thing to remember in this connection: easier to do right the first time than to redo everything later.90% of SEO work goes in Back link building. And this is hard part of SEO work.

Choosing wrong content management system (CMS)
Unfortunately, many CMS do not even have the basic characteristics of SEO, for example, the ability to set title, title page and text links (anchor). Other content management system can have these characteristics, but may be unfriendly to search engines or to create duplicate content.
Using the search-unfriendly practices in the development of the site
Sometimes marketing managers insist on using flash files on the entire site. Search engines have advanced in respect of understanding the content within flash files, but they are working with them is worse than the usual HTML-pages. Thoughtlessly can even completely blocked the search engine robots, for example, if you use links in JavaScript, which does not support the robot.

The absence of a permanent redirect (301 Permanent Redirect)
for search engines its important to use 301 Permanent Redirect.Many people forget about this.
Not checking on ‘rel=”nofollow”’ During link building
Google will not calculate back links which haves in link attribute ‘rel=”nofollow”’.
Pages with small amounts of content
Many sites have pages that contain very little information. Maybe so that the user sees in this page a lot of content, in particular, if the page contains images of products, as well as basic information, such as price. Nevertheless, if the only thing that distinguishes one page from other pages with similar products, this name, title and price, then the page will be either low quality, or duplicated.
Incorrect internal optimization using(“click here” or “more information”)
A huge number of sites still use references such as “click here” or “more information” .This is a big omission in relation to the search engine, which does not understand what is contained on the page where this link.
Irregular increasing keywords density
Sometimes people go too far in optimizing your site. They begin to create pages, saturation keyword in an attempt to improve the relevance of the site. This will immediately have a negative effect on the attitude of users, resulting in reduced performance indicator and is less willing to place on other sites link to your site.
From my practice I can ask in 100% content writer must think only about user and not about Google when write content for site.

 Waiver of investing in website promotion
Many organizations believe that work is finished after the launch of the site. They do not realize that a website needs to be moving in the same way as other goods and services. Incoming external links (and in the future, other links to your web site, company, products on the Internet) – are the main levers that use search engines when determining the relevant sites for a particular search query.