How "much" schema.org is "too much"?

[Titan552]

1. In terms of adding schema.org information to web pages, how critical is it for SERP?

2. Can anyone recommend a model of what to tag?  For example, on a single blog post I could tag the "article" and the "author", but I could also tag the logo that's in the header on every page.  How much is "enough"?

3. What is the relationship between schema.org and rel="author" tags?

Thank you!

[Titan552]

Thanks for the reply.  The link is great!

And other than "rel=author" (which I know shows up ), are there other "critical" ones to have?

[vmialik]

1. Not critical but helps and gets a message across much better visually.

2. Speaking of visually and what to tag, this infographic gives you a general start of what to tag: http://moz.com/blog/a-visual-guide-to-rich-snippets

3. Rel=author is one type out of many ways to add rich snippets described in schema.org.  Used to show in SERPs the author of the article.

Hope this helps