There are several ways to backup/manage your coins and that depends on your personal preference. The most notable and most available way to each and everyone of us is to use an external hard drive that would be offline most of the time. I actually use this and it is very convenient to me. You should buy those hard drives that has built-in encryption software to add an extra layer of security to it. Another way that I use is to have a hardware wallet for your coins. Currently using Ledger (well-known hardware wallet company) but would like to try Trezor also. This hardware wallets are created for the sole purpose of storing coins (Bitcoin, altcoin, etc.) and they provide different level of securities with the ease of usage through their software that comes with it. I've been successful in managing my coins by using these methods and would come handy for anyone out there.