What has been your Biggest Mistake in Optimising a Website for Search Engines?

Any blackhat technique are big mistakes while optimizing a website. Like including hidden text, adding excessive content density etc

I always think that things are moving fast but they are actually moving very slow.

I would say the biggest mistake in 2011 and going forward is over-optimization, that is over the top on-site tweaks and concentrated anchor text in your incoming backlinks doesn't, for example your keyword in the URL, title, meta tag, all over your page and 90% of your links for that keyword, it looks very manipulated, and hence de-optimization is a word in my vocabulary now, trying to make the site and link profile look as natural as possible, ever since I adopted this approach dancing in the serps has been a thing of the past for me...

hi
not analyzing the competition and start working without the backup plan is the biggest mistake that most of the SEO experts do.

Any blackhat technique are big blunders while applying a website. Like such as invisible textual content, including extreme content solidity etc

Some biggest mistake in optimising a website for Search Engines are

Acquiring Low Quality Backlinks too fast


Link Building with the Same Anchor Text


Wrong Keyword Selection

Competing only on High Competitive Keywords

Keyword Stuffing on Web-pages


Over Optimization of web site


Thanks and Regards

Smith Jones

I think doing black hat SEO is the biggest mistake because in the starting it's giving good result but in the last the result is worse.