Bitcoin has a way to go for easy security. At this point most everyone involved with cryptocurrency is an early adopter. That can come with obvious rewards, but can also mean inconvenience and outright loss while bumps are smoothed out.
There are stickies about coin safety and many threads on storage options, but I feel there is still room for coin security mishaps.
As Bitcoin adoption expands from those who like getting their hands dirty under the hood, users will become much less knowledgeable about safe usage common sense.
Ultimately each user is responsible for their own actions. I consider a good rule of thumb to be keeping the majority of your coins stored yourself in cold storage. I think it's fine to use services like blockchain.info, MtGox, BTC-e, etc., but don't get lazy. Get in the habit of draining your online third party account balances often. Don't leave them sitting. You never know what can happen to a service, and with Bitcoin a lot can happen.
Next, be extremely careful with your private keys. I think it's a bad idea to put 100% trust in using an online site like BitAddress.org to generate your private keys, for example. There are then two points for leaking your keys instead of only one. To have any high level of trust in generating private keys you should use very trusted software, like the Bitcoin-Qt client, which you download locally so the software can't change without you being aware.
To recap:
1. Only trust yourself with the bulk of your coin security
2. Minimize loss from events beyond your control by draining balances held by third parties often
3. When generating private keys do it as securely as possible; this includes using a local machine free from malware and trusted software which can't easily change without you being aware
Saving a private key to an online site are too risky. Some people can hack your account and get all the money you have or even your tokens. Many people are very more civilized in access the sites that you put your wallet or your private key in. So better to put or write your private key to a hardcopy or any files that can be safe to write in. Well, thank you for this kind of a thread, i get some idea on it.