Your seed phrase — the list of words generated when you set up a wallet — can restore full access to everything that wallet holds, on any device, with no further verification needed. Protecting it properly isn't optional extra caution; it's the single most important security habit in crypto.
Start with where it should never go. Never type it into a website or app, including a wallet's own interface after initial setup — a genuine wallet only asks for it once, during creation or recovery. Never store it in a cloud note, email, messaging app, or photo — all of these can be breached remotely, often without you ever knowing. Never share it with anyone claiming to be customer support; no legitimate platform's support staff need it to help you.
The standard, low-tech approach is still the most reliable for most people: write it on paper, by hand, and store that paper somewhere secure and private — not somewhere obviously labelled "crypto" or "passwords". Some people go further and stamp it into metal, which survives fire and water damage that paper doesn't. Whichever method you use, consider keeping a second copy in a separate physical location, in case of fire, flood, or theft at the first.
For larger holdings, it's worth knowing that more advanced setups exist. A multisignature (multisig) wallet requires several separate keys to authorise a transaction, so no single compromised seed phrase is enough on its own. Shamir's Secret Sharing splits a single seed into multiple fragments, requiring a minimum number of them to reconstruct the original. These add real complexity, so they're generally worth the effort only once the amount at risk justifies it.
Whatever method you choose, the test is the same: could someone who found this seed phrase move your funds? If the honest answer is yes, the storage isn't secure enough yet, regardless of how careful you otherwise feel.