Most people use at least 3 CPA networks. It is good to sign up with multiple ones, as they will have different advertisers for the same offers.
With one CPA account, I pushed a simple email submit, had a 6% conversion rate.
I changed networks, different advertiser with the same email submit, and now run a steady 17% conversion on that offer.
I would suggest trying to sign up with all the heavy hitters, such as Hydra, NB, Azoogle, CxDigital, and so on. They are a bit harder to get in but they will always pay on time and have great offers to choose from.
Good luck $$$$ :sombrero: