PPD [Questions]

Hey guys, I recently started to work out with Pay Per Download sites again and I want to know if there's any blackhat tricks for such sites other than "proxy download own files" etc. I was wondering... is there some sort of website that completes surveys and download your files for low prices because there is one earner in top 10 who one day has like 90 $ then one day later he has 400$ in one day... therefore I was wondering if there's some kind of website that allows people to complete surveys or anything like that. I am quite experienced with the who incentive stuff (PPD) but 400 $ in one day is just too much. There has to some kind of trick... spam *****? Spam Reddit?

Is there anyone who's willing to share some tips?