Most common SEO issues with Magento

[Mickelp]

Which issues does Magento provide out of the box, what should i be aware of?

What would you recommend to change/fix as soon as possible?

[Visiblics]

One of the most common SEO issues with Magento is dynamic filter pages being indexed by search engines. These filter pages are ultimately duplicate versions of category pages (with different products) with a dynamic query string attached to the end of the URL. We've created a Magento SEO plugin which can help eliminate this issue, but I'll talk about this in more detail later on in the post.

Best article about Magento SEO: http://www.gpmd.co.uk/blog/a-guide-to-doing-seo-on-magento-websites/