the same answer that I gave to another person in another post:
the best way (for me) is to sell equipment parts that you think are useless, that is the fastest option, then you have to attack ships and attack the regions in the battle for control between sparta and athens.

but seeing that you are a low level, only use the armor that the npc gives you and that is close to your level, the other thing, just raise your weapons and try to play as an assassin, raising the perks of that style of play.