First get yourself to a respectable rank, then get a good post quality. After that learn how to read and you'll find it very very easy to get into a campaign.
We have campaigns accepting newbies and jr. members. Though the pay would be bit less than the pay for other ranks, you can learn a lot at the very beginning itself. You would mold yourself in posts. You would be constructive in posts with good quality. I am sure this is what each signature campaign would be expecting such users.