Given Liquity's complexities there are several things you can do:

• Borrow LUSD against ETH by opening a Trove
• Secure Liquity by depositing LUSD to the Stability Pool in exchange for rewards
• Stake LQTY to earn the fee revenue paid for borrowing or redeeming LUSD
• Redeem 1 LUSD for 1 USD worth of ETH when the LUSD peg falls below $1

To become a Stability Pool depositor or LQTY staker, you need to have LUSD and/or LQTY tokens. LUSD can be borrowed by opening a Trove while LQTY can be earned as a Stability Pool depositor. You can also use Uniswap or another (decentralized) exchange to buy the tokens on the open market.