Stick with you sorcerer chest piece it grants you some good elemental resistance for the get go, try to go for the alva set if you are in trouble with physical enemies and save four boss souls and trade them with straid in lost bastille to get the his set and some cool spells or try to go to no man area and try to talk with the mage instructor there.
Souls arrows still are your best friends in this game,some of the utility spells are moved to mid game too so DONT, DONT try to use the homming souls arrows unless you dont have other choice, it are super slow and have a long casting time.
There is no early staff like in DS1 most of them are mid game and the one in lost bastille are more for hexes than sorceries, the best so far after the default staff is the witch staff ......so buy the cat ring and yolo to the bottom of the pit in Majula and kill the giants hidding in the black gultch to get they key, warp to majula, go to the pit and open a door to get the staff, it will be you best staff till staff of wisdom