For overview of signature campaigns, see here:
https://bitcointalk.org/index.php?topic=615953.0I doubt you'd be able to get anything as a Junior Member, and if you're very busy then this whole thing is really not for you. Campaigns require posting a lot or doing something for the advertiser.
(Also, it's not about getting paid in ETH, it's mostly BTC).
I saw some ICO projects had a signature bounty for jr members, But you can not get ETH directly. They always pay ICO tokens to you and you need sell them on exchanges.