Credit Building 101

[Kevin Sproul]

I did a search and the existing Credit Score building threads are from before the last few batches of rule changes so I thought I would start a new one. So all those who understand credit scores:

Starting from scratch, what is the fastest way to build up to a score which qualifies for prime rates?
(By from scratch I mean a kid turning 18 with no accounts/debts or cards yet or an immigrant from a place with no credit scores or credit reporting agency).

How high dose your score need to be to hit that "Prime" threshold?

PS: Yes, I understand that there are ways to invest without having good credit or using the credit you have but a good score makes it easier and/or cheaper to do many things.