I know there are many CPA networks you can find on Offervault, but hands down to Maxbounty as the top CPA network of all time. They have the highest CPA rates for email/zip free offers, and can pay up to $1.80+ a lead. As of now, I am inactive in Maxbounty due that I am concentrating on other important things. When you apply with them, be confident and honest as they are going to call you via landline or mobile phone. I hope my source link helps you.
I have read @cheezcarls' suggestion and it is a good read for newbies as it indicates the basic requirements of every network and what the newbies can expect from these CPA marketing sites. Some find it hard to get an approval from MaxBounty and other leading CPA marketing networks but letting them know your sincere intention to be part of their marketing strategy and putting up a good budget will surely make you a good candidate.