What are some good ways to rebuild credit besides paying credit cards and bills on time? We already do these things and wanted to know if there was anything else we could do.

I am trying to rebuild my credit after ID theft, a couple of problems that were mine and years of basically not having any credit reported. (I primarily use my debit card and pay cash for everything). I make good money now and am trying to rebuild in order to purchase a condo in the next couple of years. My good accounts (rental, club, cable, cell, etc.) have not reported my good credit. So how many cards should I take out that will help boost my credit score but not hinder my credit.