0. I have a credit card but I just use it like a debit and pay it off every month so there's no fees or anything. I don't like the feeling of spending money I don't have.
This is what I do. I don't make large purchases on credit either.
$0 as of my direct deposit from work yesterday. I try not to use mine recklessly, but pay it off as soon as I get paid. Only use it for concerts or going out of town, things like that. Not necessarily everyday purchases or items I have a want for.
It's good to build credit. I also got two loans last year that I paid on regularly. My score improved really good.
It's good if you're conservative and especially if you have student loans that's gonna take you a bit more time to pay off. As they hit your credit hard.