What are the best ways to get more (and sometime free) crypto?

I'm looking for things like

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Learnings:

– Coinbase learn (3-4$ on average, learnings appear every now and then)

– Revolut learn (there is DOT learn which gives you 9$ in DOT, hopefully more to come soon)

Campaigns:

– Binance campaigns (change all the time but often there are different campanges where you can get some crypto)

Staking:

– I mean what should I say. Simply stake what can be staked and enjoy the returns.

Airdrops:

– Did not find a good one so far but open for suggestions.

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What other things give you more crypto without investing fiat?