Buy the Fortnite Battle Royale Battle Pass for Extra Challenges
In Fortnite Battle Royale everyone can take part in challenges to earn more XP, but if you buy the Season 3 Battle Pass you also get special weekly challenges. This helps you level up faster even if you can't play daily.
You will typically find two Battle Pass Challenges each week, which rewards you with Battle Stars. You need to complete these in the alloted time to earn the awards, but you have way more flexibility than the daily challenges.
With 10 Battle Stars you level up your Battle Pass by one tier, unlocking more Fortnite Battle Royale skins and loot faster. You also earn Battle Stars as you play normally and complete challenge without a Battle Pass, but this is a way you can level up much faster.