Try not to go too heavy on damaging, so max out INT and then divvy between VIT+LUK (Or use Dex instead of LUK if that pierce defense really mattered). If all fails, restat with the almighty stick.
Also, do bounties when you hit hardmode for a secret magic weapon. Totally worth the investment, and if you're good with calculating; then it'll fit like a glove with the playstyle.
Potions is always important. Ignore what others may say about not using it, but it'll help out in certain fights.
Casting. Oh man the casting is there, but isn't. Favorite skills is either fireball or water bolt barrage, and everything else is just passives. Stick with a low levelled skill if you are doing it solo, or don't have enough prep time to use one. If you have neither and cast it, then...
YOU DIED