Things I have learned about General Hux from the tfa novelization:
He paces when he’s anxious, and when he forces himself to stand still (because it’s a “waste of energy” to pace), he starts scraping his palms with his nails.
He’s something of a military mastermind. Always planning, always thinking ahead.
He trusts his men and treats them without unnecessary belittling.
He studies people’s behavioural pattern and body language to be able to read them better.
He hates to admit his failures, but readily takes responsibility for them anyway.
He respects Kylo’s powers and ability to use the Force, but he is not afraid of him (at least according to himself).
He is a fucking smartass.
Even though he and Kylo hate each other and neither bothers to hide it, Hux has no problem to try and be manageable in order for them to work together more easily.
He is confident, but also very defensive.
While he is all too eager to destroy the planets that house the Republic, he protests when Snoke orders him to destroy all planets in the Ileenium system since it’s “unnecessary” and those planets could be claimed by the Order.
He is susceptible to praise.
He recognises that aggression from him won’t make his underlings work faster after they’ve been given orders, but rather rattle them, so he keeps it in.
Even though he’s obviously a good leader, he isn’t a very good team player (just look at the disaster that is him and Kylo trying to work together as equals).
He is willing to sacrifice his own men as collateral damage if he thinks it’s necessary.
He has a tracker in Kylo’s belt, and there’s no explanation as to why.