This stands for 'Do your own research'. In other words, don't just blindly trust anything that is online. Check for other sources, and ask for second opinions. Be very careful, and judicious with accepting news from one source.
Be especially suspicious of people contacting you in private, offering help about issues you posted about publicly. Virtually every time it happens, it's a scammer trying to convince you to expose your passphrase, private keys or otherwise compromise your tokens.
Don't rush into unknown projects that promise outsized returns. Any dApp you deposit your funds into has access to them. Search for the project online, and see who maintains it. Check that the contracts are verified, and audited. Look out for potential red flags.
Ava Labs team members will NEVER DM you directly on Discord, Telegram, or any other communication channel.