there are many ways, killing mob.. yes but you need to be smart if u really want to be adena farmer. First, let me guess.. you are farming with 1 toon, maybe 2?
Here we have 4 box limit and if you truely want massive adena you will use all 4 to be farming. It is simple, more chars killing = more adena faster.
FoG is one of popular adena farm zone. So make a AOE toon (mage or poler) and go there, AOE kill all day all..
So what.. you are killing mobs in FoG? Nice adena in a couple hours?? Cool.. but you are still doing wrong.
There is more ways to maximize profits..
SPOILER, make a spoiler with pole or not, but if you have a spoiler in FoG farming also u will get spoils(trash mats) like S grade parts..hundreds.. and you can sell them all to NPC for even more adena. Not to mention basic materials which u can craft with or sell!
There are many ways to make adena but i cant tell you all, good luck!