1) intelligence - they are good at adapting to various conditions and often seen as smart and able to outwit the opponent/competitor. Some cultures think this trait is more of a cunning one which might make them trickster type in the symbolic nature. For e.g, in Indian folktales and fables Fox (Lomri) represents a conman
2) Independence (often in contrast to Wolves who work in packs) - some see this nature like those loner heroes or those individuals who want freedom. For e.g., In Scandinavian literature, foxes usually represent strong willed, independent hero who is an outlaw and is anti establishment
3) Curiosity - their nature encourages exploring which means a curious mind