If you need to level up, buy armour. I can't offer any advice on which bit to get, as no doubt RNG will curse you with the same bit as a random drop a few days later. Go for the perks you like (eg. extra ammo for your favorite weapon type, faster reload etc) and don't worry too much about Intellect /Discipline until you have a few pieces to choose from. It's all about leveling up as quickly as possible so you can do the higher level activities to get even better gear.