General question about backinks

I have about 20 backinks to one of my sites. Is it better to do more or backlink those backinks for more power?

do more. much more. focus on d0f0ll0w links from strong sites. focus on IP diversity, on links with your keyword in the anchor. if the links u have are so weak they need links towards them, then they are too weak to even spend time building them. if you can automate, ok, but don't waste time on such low quality links. there are thousands of good d0f0ll0w blogs where you can comment, d0f0ll0w forums, sites that accept guest posts, etc.