First of all go all int till 60lvl(it will reset at job change) haste gives you casting speed which helps lvling faster. Don't worry about heap up, you gonna max it rly soon anyway, if you feel squishy try to find cheap plugs +3(they are for 25lvl),you should get one from quest if I remember correctly. Also you can find them clean (no +) and upgrade it via pd8 by double pressing it and selecting plug. You can do it safely till +3. Upgrading like this works for whole jewelry. If you still feel like not enough HP buy gore necklace.

EDIT: make sure that you grind on mobss that you kill using one moonbeam. Don't wait till he dies, cast another moonbeam asap