Pligg site for backlinks

I just started a pligg site, out of curiosity mainly, and I want it to be good for backlink building.
So I was wondering where I should pay attention to.

I've skipped the 'upcoming' section and all links will be published so all links are d0follow. I've changed some internal/functional links to n0follow for better flow of linkjuice.

But I'm mainly wondering about what to do in order for pligg submitters to be able to post. Should I remove captcha's as well? What is the footprint used to find sites like this? (Im not sure this footprint is still there )
Any other things I should pay attention to?

the site is if you wanna check it out

You should be careful in managing pligg site, I have experienced before of having malware in my hosting account because of auto pligg submissions by the users.

Don't remove captcha to lessen automatic submission. Install Akismet module also.

My social submitter recognize captcha ))
pligg is pure spammed