Play campaign mode. This is another efficient way to level up, as you can earn experience points for completing missions, killing enemies, and finding collectibles.
Play multiplayer. This is a great way to level up if you enjoy competing against other players. You can earn experience points for getting kills, assists, and objectives.
Use an experience point multiplier. This can be done by using a spartan xp boost or activating a double xp weekend/event.
Complete challenges. There are a variety of challenges that you can complete in Reach, which can earn you experience points. Some challenges are easy to complete, while others are more difficult.
Use a spartan XP boost. This is a consumable item that can increase the amount of experience points you earn for a limited amount of time. Spartan XP boosts can be purchased from the Xbox Live Marketplace, or you can earn them by completing challenges in the game.