A few weeks ago I got an email telling me that my password had been changed by someone on my poloniex account. So, I suppose therefore my account was hacked. Immediately I went to freeze the account and changed my password. But the thing is, I don't want to risk that happen again with a large amount stored in the exchange.
Where would be the best place to keep my BTC while I'm not trading with it in an exchange? I don't feel as if storing it on my own hard drive is very secure as hard drives can fail, and what can you do if that happens..?
it depends how often you'll need to access it. i prefer to put most of my coins into
very cold storage--encrypted core wallet.dat generated offline and copied onto a few storage mediums.
then i leave the rest of my coins in electrum wallets that use the offline signing method, which is much safer than a desktop wallet connected to the internet, or an online wallet.
here's a tutorial on how to set up an offline signing setup with electrum:
https://www.reddit.com/r/Bitcoin/comments/3g16qy/i_made_a_tutorial_on_how_to_sign_transactions/(note: it's best to use a camera + QR code rather than USB sticks, although i've never heard of successful bitcoin theft via USB stick malware + offline encrypted wallet)