It is better to avoid certain black hat SEO techniques, in making your site rank higher. Google will track those sites and ban them from their database. Though some websites may get away from being banned, they do not help you in increasing your page ranks.
Before that, how do you find whether your site has already been banned ?
1. Go to google and type in your website name in the search bar and if it says “Your search did not match any documents”, it means that the URL is not available in Google’s database.
2. Another option would be to install Google toolbar and check for the page rank bar. If the page rank bar is completely grayed 
out, it means that your site has been completely banned by Google.
So whenever you follow Search engine optimization techniques, it is better to avoid these black hat SEO techniques
1. Don’t stuff hidden keywords in your website. These keywords might not be visible to the visitors. They add these keywords throughout their website to obtain higher ranks for those keywords. Remember search engines can read your hidden text and may ban you, for high keyword density.
2. Using Alt tag, you can specify an alternate text for your images. Don't inject plenty of repeated keywords for your images using Alt tag.
3. Don't stuff in with repeated keywords to your META-TAG. Remember that this does not increase your search engine rankings and instead you may get penalized for keyword spamming.
4. Never stuff your Title Tag with repeated keywords. You may include your targeted keyword to your title tag only once.
5. Never link with any websites, penalized by Google. Your search engine rankings may go down drastically.
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