Levelling up in The Elder Scrolls IV: Oblivion Remastered is not as straightforward as in most RPGs. In the absence of a traditional XP system, you will have to level up by actually performing actions related to various major and minor skills.
This guide has everything there is to know about leveling up quickly and efficiently in The Elder Scrolls 4: Oblivion Remastered.
How To Level Up Skills
By performing skill related actions and tasks, you will gradually fill up a bar that pops up in the top right corner of the screen. While every skill contributes to increasing your overall level, the major skills selected during character creation have a higher impact.
Acrobatics
Jump long distances and avoid damage when falling great distances.
Alchemy
Create potions and gain benefits from alchemical ingredients more effectively.
Alteration
Cast spells to breathe or walk on water, open locks, shield from physical and magical damage, and alter encumbrance.
Athletics
Run and swim faster, and regenerate lost fatigue faster.
Armorer
Maintain weapons and armor at top efficiency. Worn weapons and armor are less effective.
Requires a Repair Hammer.
Blade
Deliver the slashing and thrusting attacks of dagger and sword weapons more effectively.
Block
Parry melee attacks with shields and weapons. Successful blocks reduce damage.
Blunt
Deliver the crushing blows of mace and axe weapons more effectively.
Conjuration
Cast spells to summon otherworldly creatures, summon magical weapons and armor, and turn the undead.
Destruction
Cast spells to inflict magical fire, frost, and shock damage, or reduces resistances to magic attacks.
Illusion
Cast spells to charm, conceal, create light, silence, paralyze, command or affect morale or aggressiveness.
Hand to Hand
Attack without weapons to damage and fatigue opponents.
Heavy Armor
Make more effective use of Iron, Steel, Dwarven, Orcish, Ebony, and Daedric armors.
Light Armor
Make more effective use of Fur, Leather, Chainmail, Mithril, Elven, and Glass armors.
Marksman
Deliver more deadly ranged attacks with bow and arrow weapons.
Mercantile
Get better deals when buying or selling goods.
Mysticism
Cast spells that absorb, reflect, and dispel magic, move objects, sense life, and bind souls.
Restoration
Cast spells to restore, fortify, or absorb physical and magical attributes, cure disease, and resist magical attacks.
Security
Use lockpicks to open locked doors and containers.
Sneak
Pick pockets and move unseen and unheard by observers.
Speechcraft
Use speech to persuade listeners to like and trust you.
While you will ideally work towards improving your chosen major skills for maximum benefit, some of the minor skills can also be grinded for easy gains.
Skills such as Alchemy can be used to farm potions for the leveling, with the added benefit of their sale value in gold. Armorer can be used in conjunction with readily available Repair Hammers to repair throwaway equipment just for the skill increase. Sneak could be used to prowl around towns and cities without actively robbing NPCs and attracting trouble from the guards.
That is all there is to know about leveling up fast in The Elder Scrolls IV: Oblivion Remastered.