A filename may work on your computer and still cause trouble during a handoff. Operating systems, cloud services, and applications do not all handle special characters, capitalization, or long paths in the same way. A restrained convention helps shared material travel reliably. It should preserve readable names while avoiding common conflicts, not attempt to accommodate every theoretical system.
Avoid common incompatibilities
Letters, numbers, hyphens, and underscores provide a straightforward basis for a mixed-system workflow. Windows reserves certain characters and names; a colon is therefore a poor choice for a time in a shared filename. Use something like 1430 or another agreed representation instead.
Do not rely on Report.pdf and report.pdf being treated as separate files. Case sensitivity differs between environments. Give substantively different files genuinely different names. That preserves the distinction in services that treat those two spellings as equivalent.
Look at the complete path
The individual filename is only part of the path. Several long folder names can create a very long combined path. A project may therefore fail after being copied into a deeper destination even though its files opened correctly before. Keep repeated context in the hierarchy concise and test the actual destination.
Accented letters and other Unicode characters work in many modern applications. They are not universally forbidden. If a known recipient or specific service requires restricted names, use an agreed simplified spelling for that handoff and document the correspondence.
Test a representative package
Before transferring a large collection, send a small package containing long names, a representative special character, and the full folder hierarchy. Ask the recipient to save, extract, and open it in the intended application. Seeing an entry in a download window is not sufficient verification.
Keep extensions unchanged when renaming is necessary. Afterwards, inspect linked images, workbooks, and other dependencies. Prepare large collections on a copy so the working source remains available. A suitable convention is one that works reliably in the actual exchange and remains readable to both parties.