I think that this is a bit related to what I've replied from a different thread.

I believe there are still a few that offers bounty campaigns for Jr. Members. However, signature campaigns almost no longer accepts Jr. Members. Sadly, I was trying to find one and came upon a thread where the admin announced that they we can no longer have signature links.

Here is the link for your verification: https://bitcointalk.org/index.php?topic=178608.msg28792130#msg28792130

The best suggestion would be to keep posting helpful information so that you'll receive "Merits". This will be the deciding factor if you want to be hired for signature campaigns.

Here is a helpful link from admin Theymos that talks about merits: https://bitcointalk.org/index.php?topic=2818066.msg28853325#msg28853325

Good luck and keep posting (helpful information)!  Grin Grin Grin