This is how i keep my private keys safe since i can't afford to buy a hardware wallet.
1. A complete new harddisk
I bought a new harddisk and install window 7 on it and copy all my private keys in there, i don't bother to leave this harddisk in the pc, after the copy is completed i remove the harddisk and keep it.
2.My Recording book
I have a long hard shelled book that i use for keeping records of all the airdrops and bounties i promoted because sometimes i used to forget easily so i write down my recovery seeds in this book as well
3. Flash Drive
I have a good 8gig flash drive as well that i use to copy software and files from one pc to another so i format this flash drive and copy my private keys and recovery seeds in it.
At first no one knew i am into crypto stuffs and secondly i don't share my room with anyone cos i am living alone, those who have people around them with face problems like friends going behind your back checking through your stuffs or even stealing your things, hardware wallet is still the best though.
One last thing, even though you've exercised the utmost security practices in protecting your sensitive information such as placing it in a secure medium and in a safe place doesn't mean you will be complacent with your security setup and let your guard down!
I guess you forget that there are other ways that your private keys might be obtained, maybe with a phishing technique through unsolicited emails, manipulated links and pop up messages, etc - all of this are techniques employed by intruders to gain access to your important information such as private keys, etc (without even touching your harddisk physically!). I hope you should be aware of this and be vigilant always before its too late!