Every armor and weapons is good for its purpose and if you die alot since you're using light armor you should concidering using CCs to prevent mobs from approaching you or altogether kiting mobs abit. One thing I recommend as a fellow light armor user is put all attributes into health because you sorely need it for obvious reasons. Heavy armor in PvP would defenetly make you last longer but you'd run out of magicka really fast if you plan on staying a mage. What I think is the best for you to do is experiment, throw around you gear and skills abit see what you like and what fits your playstyle, that is the beauty of ESO.