It's a major chore, but you can reach out to these players afterwards.
I have a set of macros I've used that gives 'the basics' to players that are clearly new between matches, such as 'go to Wolves' Den Pier to set up your bars and practice against dummies/duels', use your LBs, use general actions like recuperate, falling back and regrouping is better than dying and staggering your team rezzes. Sometimes, I go into more depth for certain jobs like PLD that require a bit more effort since its gotta do stuff like Guardian/Guard, and how its LB factors into that.
Usually, players are receptive and grateful. Some don't care and I try to express to them that it ruins everyone's fun (even their opponents) if they don't even try. Very few are outwardly hostile to me reaching out. If someone routinely does nothing at all in multiple games or just starts cussing me out or whatever, well, I have a template for reporting that, too.
What sucks is how difficult it is to do this. We have to stop queues, travel to their realm (if they're even queuing from there; outta luck if they're somewhere else or DC visiting), search their name and catch them with a tell between matches.
Arguably players shouldn't have to do this, but it's an MMO and I'd rather see more people try and enjoy the PvP and make em feel welcome. I just wish they made it more convenient to reach out (send cross realm tells without friends using recent contacts menu? Enable party chat after a game at the scoreboard? Enable tells in duties?) and report damaging behavior (filling out a report is very tedious. Maybe this isn't entirely bad as it might limit folks abusing the system somewhat, but often the things players get reported for are routine enough that it should be easier to correct the behavior if it actively detracts from a mode that depends on players as much as CC does).