He shouldn't be thinking about CCs just yet. Work on getting the SL taken care of first. Call the original SL company & ask about a rehab program. Anything to get that negative listing off his CR. Once the SL is handled, then start thinking about CCs. I don't mean "handled" as in PIF, but at least on a payment plan and give that six months or so of payment history first. That will also give him an idea as to how much expendable $$ will be in his budget to see if a creditor will even offer him a CC, too.
He needs to teach himself how to pay, and pay on time, first. If the SL is the only history he's had, and he hasn't managed that well, yet, then he needs to focus on that before he potentially racks up even more debt. Just give it a few months. Step #1 is taking care of that SL.