Hello as bitcoin is almost 20000$ when I was writing this, I wanted to make a post and talk about how to secure your bitcoin.
Before I show you how to, I would like to write about why you should.
A year ago I had a friend that lost his laptop.He had his private key in a txt file on the desktop.No he doesn't have any money in his btc wallet.He is disapointed.The end of the story.(This isn't real but it could happen to you and me and any bitcoin holder.)
First of all you should never ever put your private key in a txt file.Anyone ca read it.If you really want to store it on a pc put it deep in your computer and maybe with a name meaning someting else and change the extension too.Example: lib.dll
No one will try to open it in notepad as it sees it's a lib file and it's probably random text in it.
If you also put it tacticaly like in a game libs folder no one will know.
But there is one problem with this.If that pc is the only place you have that private key and it's stolen you lose access to your funds.
I recomend also writing it to a paper.But keep it in a safe place and make sure you understand what you wrote.Make sure you can clearly know if a letter is capital or not.Don't confuse 0 with o and O or 1 with I and i.
I recomend storing your private key on a new usb drive and keep it in a secure place and never access it unless you really need to.
How you use your btc address can also influence your security.Never use the same address to recive or send bitcoins as it can be traced and someone will know how much btc you have and if you are a good target to be hacked.
Use hard drive encryption to protect your data at rest i.e. bitlocker or truecrypt for windows.
personally I recommend using Linux!
Truecrypt is obsolete as it can be decrypted easily.I also use linux on almost all of my computers but not even OSx is secure.There will be allways a way.Just get a old laptop and store your keys there and never connect it to the internet.Maybe make the keys on it with armory too.
100% correct trucrypt is obsolete thanks for reminding me, was the only encryption software beside bitlocker that I have tried for windblows.
You have openbsd if you're really paranoid or you could create a paper wallet using a live cd.