Where can I get a good unsecured credit card to reestablish really bad credit?

I need to re-establish my credit; where can I get a good credit card that is unsecured and you don’t have to pay to get?

Is it better to have a secured credit card and never use it at all or to use about 20% of the credit limit?

I would really like to try to reestablish my credit over the next year or two. Even if that means only applying for a secured card and cutting it up. However, I don’t know if it is better to actually use 20% of my secured credit limit and pay it in full monthly [...]