1- Google Penalty because of Providing outbound links to banned websites: You are suggested to check your all outbound links if any website(s) is (are) banned by google

2- Linking to bad neighborhoods Google Penalty: You check that you are not linking to any bad neighborhoods, doorway pages or link farms . Bad neighborhoods include spammed websites and doorway pages, while link farm pages are just pages which contains non relevant link depository

3- Automated query Google penalty: Google penalties sometimes can be caused by using automated query tools which make use of Google’s API, particularly when such queries are made from the same IP address that hosts your site. Such tools break Google’s terms of service (as laid out in their Google webmaster guidelines). Google allows certain automated queries into its database using its analytic tools and when accessing through a registered Google API account. Unauthorized types of automated query can cause Google penalty when used excessively.

4- Over SEO optimization Google Penalty: These thing can be triggered by poor SEO techniques such as aggressive link building using the same keyword or phrase in link anchor text. When managing link building campaigns, always vary the link text used and incorporate a variety of different keyword terms. Use a backline anchor text analyzer tool to check backlines for sufficient keyword spread. Optimizing for high paying keywords like “Viagra” can further elevate risk, so mix in some long tail keywords into the equation. For brand new domains, add no more than 5 new one way backlines a week and use deep linking to website internal pages, rather than just homepage link building.

5- Website cross linking & link schemes Google Penalty: If you run more than one website and the Google penalty hits all sites at the same time, check the interlinking (cross linking) between those sites. Extensive interlinking of websites, particularly if they are on the same C Class IP address can be viewed as “link schemes” by Google, breaking their terms of service. The risks are even higher where site A site wide links to site B and site B site wide links back to site A. If you must use site wide links, make sure they are not reciprocal links. Link schemes built around links in the footer of each webpage are particularly risky. The reality is that site wide links do little to increase site visibility in the Google SERPS, nor do they improve Page Rank more than a single link, as Google only counts one link from a site to another.

6- Invisible text or links Google Penalty: Remove all  invisible text from your content and remove any hidden keywords. Such content may be hidden by using CSS or alternatively, text may have been coded to be the same color as the page background, rendering it invisible. these risky SEO techniques often cause of  a Google penalty or web site banned by goole so hidden text should be removed immediately.

7- Keyword stuffing Google Penalty: Remove keyword stuffing in your website content (unnatural repetitions of the same phrase in body text) if there are. Always use natural, well written ethical seo copywriting techniques.

8- Automated page redirects Penalty: The use of automated browser re-directs in any of your pages. Meta Refresh and JavaScript automated re-directs often result in Google penalties as the pages using them are perceived to be doorway pages. This technique is especially dangerous if the refresh time is less than 5 seconds. To avoid Google penalties, you can use a 301 re-direct or Mod Rewrite technique instead of these methods. This involves setting up a .htaccess file on your web server.

9- Link buying or selling Google Penalty: Check for any paid links (I.E. buying text links from known link suppliers / companies). There is some evidence that buying links can hurt rankings and this was implied by comments from Matt Cutts (Google spam Head) on his SEO blog in which he discuss Google seo tips. Matt states that Google will also devalue links from companies selling text links, such that they offer zero value to the recipient in terms for improving website rankings or Page Rank. More recently, Google applied a Page Rank penalty to known link sellers and many low quality directories.
 

10- Reciprocal link building campaigns Google Penalty: Excessive reciprocal linking may trigger a Google penalty or cause a SERPS filter to be applied when the same or very similar link anchor text is used over and over again and large numbers of reciprocal links are added in a relatively short time.The dangers are made worse by adding reciprocal links to low quality sites or websites which have an unrelated theme. This can lead to a backlink over optimization penalty (known as a BLOOP to SEO experts!). a Google Backlink Over Optimization Penalty causes a sudden drops in SERPS ranking (often severe). To avoid this problem, reciprocal link exchange should only be used as part of a more sustainable SEO strategy which also builds quality one way links to original website content.

Adding reciprocal links to unrelated sites is a risky SEO strategy, as is reciprocal link exchange with low quality websites. To help identify quality link exchange partners we use a simple but effective test – regardless of indicated Page Rank, if you can’t find a website’s homepage in the top 20 of the Google search results (SERPS) when you search for the first 4 words of a site’s full HTML title (shown at the top of the Internet Explorer window) then undertaking reciprocal link exchange with that site may offer few advantages. Don’t forget to check that prospective reciprocal link partners have a similar theme as your homepage too.

Thin Affiliates and “Made for Adsense” sites

It’s a well known fact that Google dislikes affiliate websites with thin content and the same applies to “made to Adsense” sites. Always make sure affiliate sites have quality original content if you don’t want to get them filtered out of the search results when someone completes a Google spam report. We have had personal experience of affiliate sites acquiring a Google penalty, so don’t spend time and money on SEO on such sites without the right content.

11- Check Google Guidelines
Read the Google Webmaster Guidelines thoroughly and check website compliance in all respects. Since early 2007, Google may alert webmasters via the Google Webmaster Console who they feel might have unknowingly broken their guidelines to advise them that their site has been removed from Google for a set period of time due to breaking one or more of Google’s Webmaster Guidelines.

However, blatant spam or significant breaches of Google’s rules will often result in a site being banned, with no Webmaster Console notification. Where notification of a violation of Google’s guidelines is received, it usually encourages the webmaster to correct the problem/s and then issue a re-inclusion request to re-include their site. From my experience, after this is done the website will usually regain its original ranking, having lost no trust.

12- Google Webmaster Central

According to Matt Cutts’s Blog, Google is improving webmaster communication with respect to banned and penalties wesites. Google is now informing some (but not all) webmasters the cause of a website ban or penalty, via their excellent new Webmaster Console. In addition, a Google re-inclusion request can be made from the same interface. For this reason, if you’ve been hit by a web site ban or penalty, it is worthwhile signing up for Google Webmaster Tools and uploading an XML Sitemap onto your site and then to check site status in the Google Webmaster Console. This is an easy 10-15 minutes job and may help to identify the cause of Google Penalty and fix for the problem!
When all issues are fixed then send a re-inclusion request to Goolge