What are the minimum requirements for selling your signature space to advertisers? I'm curious as to how this actually works and if you actually get paid? All it basically comes down to is, your promoting they're services right?
You should look to each campaign rules.
Here, an overview of current campaign accepting members. Also, to check if they pay (or may pay) looks at campaign thread OP trust score & history. Also, you my wish to use signature campaign with escrowed funds.