Increase Intelligence
Increase Willpower
Use the Atronach birthsign
Use Fortify Magicka spells or potions
Wear items with Fortify Magicka
Wear items with Fortify Intelligence
Use enchanted gear with Magicka bonuses
Join the Mages Guild and use spellmaking/enchanting
Use Altmer, Breton, or Dunmer racial bonuses
Level up and choose Intelligence increases
Use the Apprentice birthsign
Use shrines or effects that restore or fortify Magicka
Use Sigil Stones with Magicka bonuses
Use the Mundane Ring
Use the Necromancer’s Amulet
Use the Mage Stone if available in your version/mods