Would it be better to split a file and then encrypt, or vice versa? Assuming that you are paranoid before storing your file (distributed across a shared location), which will be the best case scenario: splitting the file first and then encrypting or encrypting first and then splitting?
Either could be implemented securely, but if you encrypt first and split afterwards, you can use standard tools and get everything right more easily. If you used the opposite order, you would have several pitfalls to deal with:


With password-based encryption you would either have to derive the key many times (spending resources that would be better used on additional hashing) or have a separate key derivation step and then use the key on all the parts.
If you had a single key used multiple times, you would have to make sure IVs are unique, when with a single-use key you can forgo it completely.
To fully authenticate the encrypted file you would need to add some metadata or a whole-file MAC, instead of simply using authenticated encryption on each part. Otherwise an attacker could be able to drop or reorder the parts.
As a practical issue, if you are splitting to a certain target size, you would have to take into account the expansion caused by encryption IVs and authentication tags.