An organized structure to your data pack's folders and file names always helps you understand your code better and leads to less bugs. Place files that have something in common in the same folder, and name them based on what their purpose is.
Consistency in naming stuff like tags, files, and scores can help keep you sane. Always have a clear structure in place, such as prefixing tag and objective names with your namespace (namespace.name) and giving tags different categories (namespace.entity.name, namespace.block.name).
If you are unsure of how a good structure could look, you could take a look at some vanilla assets, such as the lang file or the built-in data pack, as well as get ideas from looking at data packs that other people have made.