This was an internal Google presentation...
Myth: Duplicate content will penalize your site
Comments:
* Don't worry too much about duplicates on your own site.
* We're good at ignoring duplicates.
* Make it easy for us to find the preferred version.
* Help us to crawl efficiently.
* Be reasonable when re-using content from other sites.
Myth: Mixing HTML/XHTML will break verification
Webmaster Tools accepts both kinds of meta tags, regardless of your page's code or doctype.
However:
* The site must be reachable!
* The verification code depends on account + site URL.
* Sometimes it takes a second attempt.
Myth: Getting listed in 1000s of search engines and directories is important.
Nope.
* Do you use 1000s of search engines?
* Most search engines will find your site before you find them.
* Submitting does not significantly change things.
* Your email spam will grow exponentially.
Myth: Participating in AdWords, AdSense or Analytics will help or harm your site.
It won't.
* They're great products though!
* Google Analytics is a great aid to make the most out of your site.
Myth: If a keyword is important, it's important to repeat it in important locations on important pages so that the page looks more important to important search engines.
Please don't stuff keywords into your content.
* There is no optimal "keyword density."
* Write naturally, write for your users.
* Too many mentions distract users.
* However: don't hide what you really mean!
Myth: Using XML Sitemaps will make your site drop
Nope.
XML Sitemaps are useful:
* They help search engines learn about your content.
* They help YOU to learn about your website.
* Lots of CMS have them, lots of generators are available.
* Keep them up to date!
Myth: PageRank is dead / PageRank is everything!
PageRank is a measure of the quantity and quality of links to a page.
* Google uses PageRank.
* Google also uses over 200 other factors.
* Toolbar PageRank is updated a few times a year.
Myth: Resubmitting your site regularly is vital
Nah.
* Resubmitting does not change crawling, indexing or ranking.
* Once we know about a URL, we'll plan accordingly.
Myth: Once your site ranks high, don't touch it
Some things get better when left alone. Websites don't.
* Happy users will return.
* Give users something to look forward to.
* Changes in ranking can and will happen.
* Other sites won't stand still!
Myth: Valid (X)HTML will make your site rank higher
<h1>nah</h2>
* Most of the web uses invalid code (less than 5% is valid!).
* Browser are used to it, search engines too.
* Extremely broken code is very, very rare.
However:
* Valid code may work better on more browsers.
* Valid code makes finding & fixing some issues easier.
BONUS MYTHS
# Using "disallow" in your robots.txt will remove your site/page from the index.
# The more links the better.
# The only important goal when making a website is getting it listed first in search results.
# It's best to let old URLs return 404 so that the new structure is naturally discovered.
# Using "Index, Follow" in robots meta tags is important.
# Hosting your site on a shared IP address will cause your rankings to drop.
