If I have a few mins to kill during the day (usually when waiting for ETH/BTC to hit the exchanges from my wallet) Ill sign up for an airdrop or two. Most of the ones that I have either haven't hit exchanges or are worth under $1.
TRON (TRX) was the first one for me that actually did something.
500 free TRX peaked at ~$30 and is currently worth ~$19
HODLing!
Started crypto by hunting for airdrops last October. My biggest till date was Hawala token (HAT). Got 100 of it. The price mooned after a some weeks to the worth of $2200 for just 100 HAT