Some internet sources consider that organizing a link campaign, the number of new links per month should be less than 10 % of the overall number of links that the site has. Do you think it is right?
That 10 % refers to all the links ( outbound, inbound )?
Or does it refer to the unique links ( considering several links from the same site a s an unique link)?

My impression, in these days, is that it’s not necessary a big number of links, but few good links per month.
I think that Google is implementing something like a “sandbox” for sites getting too many links in a short term.

I think that is largely dependent on the level of authority your site commands, but even more dependent on the quality of those links.

If you have an established authoritative domain I don’t believe there are negative implications with getting too many links too soon. There are many examples we can point to where a site can naturally gain thousands of links within a few days such as an exclusive news story breaking on a site that gets picked up by the media and blogs, or a new widget getting picked up thousands of customers.

With a newer site I might take a more conservative approach when building links…but the same concept applies.

How many links do you think some site acquired within the first few days it launched? Hundreds? Thousands? And it wasn’t penalized…..

I’d focus on what links do count and share how and where I find them. All the link building tactics we’re fond of still work: reciprocal links, three way links, using article directories, adding your site to a million general directories, and even paid links, why ‘even’? because everybody is scared whether this is the right way to get links today as it was announced google doesn’t think so and even more this search engine will be punishing such guys who sell links but by the present day it’s only a theory. All links count in some way, even those cloaked in things like nofollow, robot.txt, or a third party tracking code. These types of links may not be SEO friendly, but they do work and depending on where they sit, can go a long way toward boosting your visibility.

Here’s the short list of guidelines I follow when building links to influence rank:

- Place links on indexed pages

- Use multiple variations of anchor text and point to optimized internal pages

- Links should go from thematic sites

- A page where your link is placed must contain no more than 50 links

One more thing is PR. Many webmasters require PR on pages where their link will go from. I don’t think that PR is so important nowadays I personally think that the linking page must be indexed in Google and if this page does not have PR be sure it would get some one day. When I receive link proposals PR is the last thing which I’m looking on when link exchange, the more important thing is for example google indexation, number of links on the page where my link will be placed or the age of the domain of my potential link partner.

Over the years, I’ve found the challenge in linking is less about the tactic and more about using smart SEO on quality resources.

Remember: all links count.