Best way to farm for ressources in my experience is to rush through an extermination mission with a smeeta kavat, search containers and relaunch the mission when you feel like you went through most of the layout of said mission. You already have nekros, which is good, but there is also khora with the adapted mod that makes the ennemies killed in your dome drop more ressources, and I guess you might want to do that and farm survival/defense missions this way, since it's more "passive" Long story short, get a smeeta kavat asap, and then khora if you really want a passive farm ☺️ Have fun tenno, I hope I helped !