Maybe this was an obvious choice, but a BIG KUDO for electing to make all of the Tileset file references in the .tmx files as RELATIVE refs! It might have been easy/tempting to make them absolute refs, which would lock them to the individual's PC file structure. Instead, once the Tiled .tmx is loaded, the relative refs can go find the Tileset (and other) graphic files with ease (assuming of course they are in their relative place).
Why is this a big deal for me? I am working with a team on a WWII game, and we are using Tiled to produce maps. We elected to put the Tiled files all out on a shared GoogleDrive to facilitate teamwork. And because the internal refs are all relative to the main .tmx... once ANY of us navigates to and loads that .tmx, all of the rest of the support files (graphics, etc.) get picked up automatically via those relative refs on GDrive. Ergo: Very easy to work as a team!
So, a kudo for that choice!