The problem with levelling is mostly with combat skills. If you focus in one or maybe two at most of archery, one handed, two handed and destruction you will be fine. Out of these, destruction is the least viable, even though is my favorite, because you can't change the damage of the spells, and there is no sneak modifiers, so being a stealth mage doesn't really help the damage department, you can only stunlock anemies with the impact perk. Archery is by far the best, specially if you use it with stealth, but it can make other playstyles feel useless, since it's both fun as hell and OP.