There’s already great suggestions here for earning credits, and while some responses have been a little sharper than is conducive to a genuine exchange (on both sides) there is genuinely good data for new players here.
I do agree that perhaps the game would do better if it was clearer that those lump sums you get in the beginning are special one-time credit payouts.
I don’t think it’s a bad idea to have some way to sell back loadout cards (though of course the credit value would have to be fairly low to prevent abuse as in most f2p games). They can’t give too many credits away because the credit sink is limited based on individual player wants/needs.
Things I’d be curious about for credit bonuses:
I wonder if they could implement a kind of game loyalty credit bonus. Like if you play at least two games three days in a row you could get a lump 1k credits. 5k credits for seven days in a row, and maybe 15k for 30d? Eh, might be better to cap it somewhere so it’s not a little too easy. I’m not certain if something like this would be easily possible depending on how things are on the back end of the game.
I think it would be cool if they had optional unique missions on special days (that are separate from normal missions), “Revive 3 Players” for Valentine’s Day, “Finish off X Players” for when large sports events are occurring, “Melee x Players” for Halloween, “Turn x objective(s)” for Christmas/whatever winter holiday you celebrate, etc. Then again, I’m very fond of mission-reward systems in shooters.