My personal recommendation is as follows:
At least two separate backup drives for full mirror copy of your brain directory (use Karens Replicator or similar). The backup drives should be encrypted (use Truecrypt or similar). Preferably keep one backup in a separate location. Create regular brainzips as secondary backups (without attachments for speed) and ensure you do primary backups on your drives every one or two days. Karens Replicator allows incremental backups which means you can run it regularly and quickly.
Always backup before upgrading. Export a copy of your favourite accelerators and themese into a thought for safekeeping.
This backup strategy is infinitely more effective if you keep all your files within PB.
Be overly diligent as habit and your brain will remain robust for decades.
TB8022 32bit Java 32bit Version 8 Update 141 Testing 9.0.224 Windows Firefox, Office 2013 Pro Plus 32bit 64bit Win10Pro 64bit Primary Laptop, 8GB RAM, Intel Core i7 64bit Secondary Laptop, 64GB RAM, Intel Xeon E3 Brain user since zygote