I'm near the end of DS2 with a caster, first playthrough and first caster in any DS game. I'm minmaxing Int and Atn for damage and speed (some Vgr cause I got oneshotted by a lot of enemies). I had an easy time up until late game, i think I rushed some areas too much making me and my stuff underleveled. So my tip is, keep your shit up to par and you're fine, easier than melee.
Haven't done any hexes though. that's for my next character
Edit: Oh, I forgot. Since your attacks are finite, you have to think of areas between bonfires and bosses more economically. I'm usually in explore or in rush mode, nothing in between.