Use your Belt Items wisely. Use your Belt Items as shortcuts to your inventory items. Then you can access all Health potions from one Belt Item slot. Keep a good stock of emergency scrolls on hand. They allow you to escape quickly, or, in the case of Resurrection, to revive a fallen comrade.
Skills can be more important than spells.
They allow you to perform magical feats without using Mana, and that becomes important the farther you explore. As you explore Ardyl, you'll come to a stockade. Inside, you'll find Drakus the Antique Dealer. He asks for your help finding the Sun Cross, an artifact he says was stolen by the Disciples of Kaliba. The path to the Sun Cross is the path to your first Crystal.