Even with no credit you still have a credit rating. A student just out of college with no credit history can still have a credit score of over 500. I don't really know how this is possible, but it is. My oldest son graduated from college with about $20k in student loans. Of course he had Summer jobs, but never borrowed money. He had a checking and savings account, but nothing more. He was able to buy a 2009 Toyota Corolla right out of school with the new job. They offered him a $1500 College Graduate rebate too.
So, I'm not sure how you can have a decent credit rating without ever buying something on credit, but he's living proof.
Jim Smith