Google has published a new, or vastly revamped, document on SEO link best practices. The previous document was just on how to make your links crawlable but the new one adds tips on anchor text placements, how to write good anchor text, internal links within your content and external links from other sites.
As a reminder, last November Google said external links will be less important as a ranking factor in the future and said shortly after that they were less important now than earlier.
The new document can be read here and you can compare it old document on the Wayback machine. Here are screenshots comparing the two.
Old document:
New document:
So as you can see, Google added:
- Anchor text placements
- How to write good anchor text
- Internal links within your content
- External links from other sites
Forum discussion at Twitter.