If you are looking for a bitcoin paying campaign for junior members try these campaigns:
★☆★ Bitvest.io - Plinko Sig. Campaign ★☆★ (JR-Hero Accepted)
★☆★ 777Coin Signature Campaign ★☆★ (Jr-Hero Accepted)
And for alt coin signature campaigns, you can just check it by yourself in the Bounties section and in most of the thread bounties are also there on those threads of any campaigns at that section. And for the airdrops, it's mostly found at the Tokens (Altcoins).