Before buying any serious amount of BTC user must ensure:
1. Software that he uses actually encrypts wallets (BitcoinQT by default does not!).
2. His wallet is backed up in 3 places.
3. Backups actually work and he tried them.
4. His computer is not infested with malware.
5. He has multiple wallets and money is spread across all of them.
So that if he one days makes a payment, enters a password and virus steals his coins, he will not lose everything.
Blockchain.info is a great service, but only when you enable 2-factor authentication (otherwise your encrypted wallet can be bruteforced offline) and make sure you get backups by email.
Finally, everyone should remember:
THERE IS NO "FORGET MY PASSWORD" BUTTON.
If you own your coins, be it in BitcoinQT, Electrum or Blockchain.info, you must own your password. You lose it - you are done. People are not used to it. They should be.