Not your key not your coins.

Get all coins off exchange. Take self custody.

Get a Ledger or Trezor hardware wallet (This way you can access them anytime). There are a bunch of youtube videos on how they work.

Then make 3 seed backups in steel washers (or titanium). And ideally encrypt them with a simple cipher (or use a passphrase and store that separately)

Low cost, affordable, easily scalable, indestructible, fireproof 1400°C (a house fire is around 1100°C), waterproof, corrosion proof, shock proof, earthquake proof, offline cold wallet, seed or passphrase backup.

https://i.etsystatic.com/41503409/r/il/689efd/4813988559/il_1588xN.4813988559_fcds.jpg
Picture taken from here: https://www.etsy.com/listing/1434977816


More information on that topic here:

https://jlopp.github.io/metal-bitcoin-storage-reviews/
https://incoherency.co.uk/blog/stories/diy-cryptosteel-capsule.html
http://bulletproofbitcoin.com/
https://blog.lopp.net/a-treatise-on-bitcoin-seed-backup-device-design/
https://www.econoalchemist.com/post/backup
https://blockmit.com/english/guides/diy/make-cold-wallet-washers/
https://bitcointalk.org/index.php?topic=5389446.0