Potions can be used exclusively for most of the game, though healing spells will save money not having to buy health poultices. Healing spells come primarily from the Creation and Spirit Healer mage spells. Health poultices come in various qualities ranging from 50-200 health healed. This is done in Dragon Age: Origins primarily two ways: health poultices and healing spells. Since your character will be taking most of the damage, they need to be healed. Ideally, all the enemies are attacking your resilient warrior.
This way your physically weak mages and rogues in the back don’t have to worry about their health much. The emphasis is on keeping yourself alive while keeping all the monsters focused on attacking you. Wearing a shield increases your character’s defensive capabilities, so this is the tank build. I will update this to support level 30 when I beat the Awakening expansion. Note: This build currently is only for the base game ending at level 20.