I just finished my filling out all my codes and buying my sellers and even signed up for prime so I hope it correct and I get some good buys,
It could be anything. How impressive the landing page is. How much mass appeal the offer has. Is the offer specific or broader, more broad will get more optins, but more specific will get fewer but more targeted subscribers. How easy or complicated the offer is. We'd suggest you test different landing pages and see which one works best.
Hope this helps.