Hi.

I want to encrypt NVMe/SSD drive. I'd like to know if I should perform full disk encryption instead of encrypting each OS separately. I want to have a dual boot laptop for Windows 10 and Linux OS (preferably Mint or Ubuntu). If I'm only using Windows 10, I'll just use Bitlocker (tried before) or VeraCrypt. The main OS will be Windows 10 home (will be used by other members of the family). It's a new laptop with AMD processor. I still want to access my files on Windows under "C:\Users" when I'm using Linux and I also want to access my Linux files when I'm using Windows. Sometimes there are files that I leave on "downloads" folder in both operating systems. I share the laptop with other people at home and they will have their own user account on Windows only.

I also want to create a logical partition or logical drive on Windows 10. It's for common files like that we can share.

Based on the Windows 10 Disk Management, the current disk has EFI system partition (disk 0, partition 1), Drive C (boot, Windows 10) and recovery partition (disk 0, partition 4). It was setup this way when I received the laptop. Type is "basic" disk. Partition style is GPT.

I'm planning to use an external drive to backup my data. I'm also planning to encrypt it.

I have tried dual booting Windows and Linux few times but without encryption. Need some guidance on encrypting both OS.

Suggestions please?

You need to encrypt the operating systems and not the full disk.
Linux needs an unencrypted boot partition and the filesystems and tools to encrypt/decrypt them are too different anyway.

Regarding an external disk: if you want to use it with Linux AND Windows you can encrypt it with Veracrypt and format it with NTFS. IN this case both Windows and Linux will be able to use it.

Can I still access Window's My Documents from Linux and vice versa?
Thanks.

Yes, provided you encrypt the Windows 10 partition with a method / tool that Linux can decrypt.
I'm only aware of Veracrypt / Truecrypt but others might exist.

BTW: I did that in the past before completely getting rid of Windows (2 years ago).

Edited to add:
I'd rather use a dedicated partition for your documents, so you don't (accidently) mess with the Windows system folders from within Linux.

I haven't decided yet if I will create separate partitions for these but is there any partition that I should not encrypt?

bin/ dev/ home/ lib/ misc/ opt/ root/ tmp/ var/
boot/ etc/ initrd/ lost+found/ mnt/ proc/ sbin/ usr/

There is no (little at best) point in encrypting anything except /home - and as pointed out, it might only be a subset, say /home/bboyukoy/Documents.
Make sure it doesn't hold files you want to share with your other users, else they will need to know your (secret) passphrase.

Thanks.
Would you recommend encrypting Windows first before partitioning the disk and install Linux in another partition and encrypt it too?

No. I'm a great believer in KISS.
Resize the Win partition(s) first, and leave the space unallocated for later Linux install. Then encrypt the Win partition(s) as needed then install Linux. I've never looked at veracrypt, so z80 will be able to advise you there - I believe it shouldn't matter where you encrypt the shared partition from, but I'm happy to be correcterd.

If you use Veracrypt I'd suggest to encrypt the Windows partition from within Windows.
Then install and encrypt Linux using LUKS (you can't access the Linux filesystem from Windows anyway) and finally install Veracrypt on Linux to mount the Windows partitions.

Edited to fix typos