So, I have a private pr2+, domain age 1y+ tumblr and blogger network, with comments disabled, etc. I have only posted a few links on each site, and page authority is all 29+ trust flow above 20. I don't want to get revenue from these site, but point them to my main 5 money sites. What is the absolute best free way to increase the link juice to these MANUALLY, for FREE. 10 tumblrs, 3 bloggers (not big by any means, but it's a start.) Thanks!