Have him join a credit union like BECU and DCU.
Has already been a part of BECU for awhile
Well, there you go. BECU. They offer a "low-rate" visa (as low as 8.90%) but if he's been banking with them he might be able to get their cash-back visa that pays 1.5% cashback on everything with no AF and a low APR (as low as 11.90%). Either one of those would be a great first card and approval odds are higher if he has account history with them. Keep that for a year or so and then branch out to other national lenders.
^ Smart move on waiting on BECU. They have the no frills, no rewards Visa starting at 8.90-19.90%
You can have him try Citi's prequel site to see if there are any hits.
Have him try the other prequal sites too.
You'll know where he stands based on the offers or no offers.
100% false. Pre-Quals are almost never given to anyone under age 21 regardless of true creditworthiness. I had no pre-quals for all but the Discover card I have with the reason for denial being under age 21.