According to my personal experiences airdrops, bounty programs and participating in testnet can be profitable if you know how to find them. For example the:
Haven1 Blockchain and Haven1 Testnet.
Staking your crypto can help you earn a continual source of income, and that can be especially advantageous if you’re a long-term buy-and-hold investor or looking to stack up some coins. The rewards vary from coin-to-coin, but those for more speculative coins tend to be higher.