The most popular is certainly advertisements. If you have a good sized platform, whether that be YouTube, Twitter, or even here at bitcointalk, you will likely be able to find an advertiser willing to pay you in order to have exposure to your network to advertise their product or service. If you aren’t an influencer, you might find that staking coins like ETH & BNB or providing liquidity on Uniswap or Pancakeswap are also popular ways to earn crypto.