How do I obtain a credit card if I'm under 21 after February 22nd?

Under new law anyone who is under 21 cannot apply for a credit card unless they have a co signer or have sufficient income. Im 18 and eventually want to sign up for a credit card online. What proof of income do i need checking account, a check that is from a job, or just enough money in the bank to pay off the bill. Most credit cards that i found for limited credit history or none have applications online. When the time comes how do i prove my ability to pay off the bill when I apply online for a card so i am approved.Thanks. Please don't mention co signing because i don't want to put my parents credit history on the line and they don't want to anyways. I tried looking for secured credit cards and one from public savings bank said they are not offering their credit card for people under 21 only 21 and older. So please even if its a secured or basic credit how do i get one and show proof of income online mostly Thanks