What SEO practises/activities can have a negative effect on search engine rankings?

[083]

As the question states, what types of SEO activities would have a negative effect on your ranking on the SERPS for Google & Yahoo and worse still could get your site taken off the index?

[Ace Savely]

The most negative is spamming your link/URL

Whether that is by Comments on Blogs, or Profiles on Forums .. The same rule applies.

By the way - Don't waste your $$$ on the wrong kind of backlinks - They won't work.

Since the Google "Panda" update a lot has changed.

Google has moved the playing field and simple text links are almost counter productive, Pyramid linkbuilding is no longer worth the effort but Contextural Links will get you an almost immediate SERPS improvement.

Most of the backlinks you will be offered today will be either, simple text on blog profiles or blog comments.

Tens of thousands of both can be done in 24hrs using Scrapebox, and because of that Google is now giving simple text links less weight in SERPS.

If you watch the latest video by Matt Cutts, Google's own guru, you will learn that contextural backlinks now have the most value.

Contextural backlinks are links placed inside an article or blog post that are in the context of their surrounding text, so they look natural.

For example an article on firefighting might have links to a firestation URL. These are quite time consuming to create and invariably need an image to get maximum Google juice.

For anyone planning to create backlinks I recommend you to take 3 minutes to watch the Matt Cutts video on http://www.autoseosystem-dot-com

If you recognise the change he speaks about. then afterwards use their FREE software to create some contextural articles embedded with your own URL.

[raysor]

Paid for links.
Duplicate content.
Anything that looks like attracting visitors for the wrong reasons.

[958]

Buying links from "link farms", or participating in link exchange schemes known to Google to be essentially the equivalent. Study the Google Webmaster Guidelines (link below).

[Andrew Symonds]

keyword stuffing
paid links with unrelated sites.
links from bad neighbors