What are the best practices for archiving and backing up your audio restoration files?

I would suggest that the WAV or FLACC format must be preserved as it is a lossless format. MP3 and aac have compression in them. I would want the real file rather than the one with alteration of some sort!

It's best practice and industry-standard to keep your audio files in at least a 24-Bit 48kHz Wav. file or any other widely accepted lossless format for three reasons: (1) as this preserves data, thus in-turn, preserves the integrity/originality of the audio signal; (2) future-proofing and safety precaution, just in case something prevents you from opening the original project file; (3) compatibility across multiple platforms. Best to be safe than sorry.

I create a lot, so I organize and back up meticulously using the trinity: the machine, the SD card, and the SSD. I do this annually to ensure redundancy—if one fails, there's a backup to the backup. While I use cloud storage, I'm skeptical about what happens to my content after my time. I want my children('s) or beneficiaries to have full control over my works in perpetuity.

Directory or File structuring is very important. Anyone who would be working with LINUX OS will understand this. Same concept is applied in audio engineering work as well. There should be a defined hierarchical structure of your files. A simple bash or python script can then be used to make a list of which file is saved where. Naming convention must be set for each folder and audio file or associated DAW file.

Saves plenty of time as this prevents you from guessing where your files are, and second, tells you exactly what files you are looking for in the midst of other versions you might have. It's important to keep your folder structure following each step of the process. For example, as a mix engineer, my folder structure looks like "D:\Projects\ArtistName\ProjectName\Recording\". After recording session, I'll Save As and create another Folder and File called "Edit" and so forth. I admit it's tedious, but, again, it's all about staying organized.

Backup occasionally and after every session on multiple drives and if you have space and the budget for cloud services, I would highly recommend so.

Backups have to be regularly maintained. One way is to manually do it in a separate hard drive or whatever media you are using. You can backup to a cloud. It can be automated using cronjobs or whatever tool is best suited to your needs!

I always keep at least three copies – one on my main work drive, one on an external hard drive, and another on a cloud service. I organize everything by project and date, and I'm religious about including all the original files, project files, and final masters. I use checksum verification to make sure nothing's corrupted. For really important stuff, I'll even throw in an offline backup on a separate drive. I always save in lossless formats too – you never know when you might need to revisit a project. It's a bit paranoid, but it's saved my bacon more than once!