Welcome back! Since you’re interested in joining signature campaigns, merit is not your only problem. You have negative feedback on your account, campaign managers usually do not accept applicants with negative feedback into their campaigns, it gives the company you’re promoting a bad look. I think you should work on repairing your reputation first before applying for campaigns.
I am doubting if it still the original owner of this account that still posting from it, based on this sort of question it's something that would be expected from a newbie or someone who has been here but had not gotten any growth at all.
You have gotten the merit of a legendary member only to come back to ask for ways to earn few merit.
I guess you missed his responses on that subject. He already addressed the issue in the first three comments in the thread.