Common advice is to keep your currencies safe by placing them into storage. I feel this is risky considering coins have dumped to all time lows within short periods of time. The alternative would be to keep them on an exchange and set stop losses, however, this is also risky as exchanges or your account can be compromised. How do you manage these risks?
Since you seem to talk about altcoins, I'd say keep them on exchange and use stop loss orders, because the risk of a coin crashing is much higher than your account getting hacked. Just make sure to use 2FA and password manager with truly random password for both your account and email, and never install any risky software on your device to avoid getting malware.
If it's Bitcoin, or some not completely bad altcoin like Ethereum, and we are talking about big amounts, then you should use cold storage.