Mana potions and minor healing potions are a good way to level up your potion making skills.

You can bring ingredients to mix them inbetween fights. You drink the vials and mix more. It is good as long as your vials don't break. You can buy more minor healing potions and mana potions from Mira.

There are 2 potion quests on IP too.

The potion quest (Mixture Mayham) no longer grants any xp in the skill.

Also, the Wine Quest in MM is a must before you start making these two potions as it allows you to purchase wine at 37.5% the normal cost (20 bottles for 15gc each).