Most crypto losses come from user error, phishing and compromised devices rather than the blockchain itself. That's good news, because those are all things you can control.
Protect the seed phrase
Write it on paper or metal, keep copies in more than one secure place and consider a fireproof safe. Never store it digitally in photos, notes, cloud storage or email, never type it into a website or pop-up, and never discuss it publicly. Splitting the phrase into parts held in different places is an advanced option for bigger sums.
Use proper two-factor authentication
Choose an authenticator app such as Google Authenticator or Authy over SMS, which is vulnerable to SIM-swap attacks. A hardware security key is better still. Turn 2FA on for your wallet and your exchange accounts.
Keep your devices clean
Update your operating system, run reputable antivirus software, avoid public Wi-Fi for transactions (or use a VPN), don't jailbreak or root your devices and install apps only from official stores.
Check every transaction
Before each transfer, check the start and end of the address, the coin type and the network, such as ERC20 against TRC20. For anything sizeable, send a small test amount first and wait for it to land before sending the rest.
Spot the scams
The usual suspects are fake wallet apps and browser extensions, phishing sites, giveaways that ask you to send crypto first, fake support staff asking for your seed phrase and investment schemes promising guaranteed returns. Check the publisher before installing anything, use bookmarks rather than links, and remember that real wallet support will never ask for your seed phrase. Our UK guide to avoiding betting scams covers the wider picture.
Bigger bankrolls
With larger sums, add multi-signature wallets, which need more than one approval, keep daily betting funds in a separate wallet from long-term holdings, store most funds offline and spread backups across different locations. A sensible rule: keep only the next week or two of betting money in a hot wallet and move more across as needed.