I'll update this topic in order to inform those who maybe are reading it and also had doubts about how to win guiles. I actually found a good way of doing it raising my Arcanist a little and going to fight.

Especially, I managed to obtain a lot of money with the quests, levequests, etc. (Around 5000 guiles, and that's a lot for me having in mind that my average quantity was around 200). The way I most obtained money was with something called "Levequests" and "Guildhests" or something like that where you do a party with others and go fighting, these methods are faster than a FATE and reward more guiles.

At the beggining all those things of the levequests and party were confusing for me, but are quite useful for achieving fast guiles.

I hope that if someone did also have doubts about how to achieve guiles but didn't want to open a new thread because this one was active found this information helpful.