If you have an appreciable amount of assets (>$10m) you'd put some amount in a special Tail Event Protection fund who know what they are doing and will invest in a combination of volatility linked derivatives, risk-off assets (short dated bonds, precious metals, rates, etc...) and dynamic equity shorting strategies. They will do so with some amount of finesse, as many of the most effective tail hedge strategies cost a lot of money to fund. Unless you do the analysis yourself, which is anything but trivial, it is extremely unlikely that you'll do a good job at judging where the tradeoff should be.
If you have less, generally the best advice is to do nothing and weather it out, because the truth of the matter is that practically nobody can time the market, not even on the horizon of years and any attempts to do so will cost you more than doing nothing would have.
There is no silver bullet unfortunately. Think of it like this, if there was a cheap and easily accessible protection against crashes, people would pile into it and make it ineffective or expensive. Which is exactly what happens.