How about giving brand new players a time limited bonus of premium, perhaps 6 slots (tank and plane), medpacks and perhaps ammo or grenade bags. Let them really experience enlisted when first starting… not anything higher than BR2 but enough stuff to give them an idea of what they they can earn over time.
Now how long would they have this a 2-3days in game time, to really give them an idea.
Thoughts on suggestions welcome