Compression is not organization
You can put a thousand files into a ZIP quickly, but if the source folder is messy, the mess simply moves inside the archive. Before compressing, remove temporary files, organize folders, and use names you will still understand months later.
ZIP or 7Z?
ZIP is the easiest choice for exchange because support is extremely broad. 7Z can provide better compression in some cases, but it is not what I would choose when the recipient may be using a limited device or application. Ask whether you want the smallest file or the fewest opening problems.
Do not nest folders for no reason
One common annoyance is opening archive.zip and finding a project folder, then another folder with the same name, then the actual files. After creating an archive, open it yourself and check that its first level looks like what the recipient expects.
Check the archive after creating it
The simple test is the best one: open the archive, extract one or two files, and check their names. For an important archive, keep the originals until you have confirmed that the compressed copy is healthy and extractable.
A good archive saves future work
The point of a ZIP file is not only saving space. It is also a way to deliver a group of files as one unit. A clear structure and understandable names make the archive useful long after it was created.
Compatibility can matter more than a small size gain
Some advanced archive settings save a little more space but require specific software at the other end. If the archive is going to a client, university, or someone whose device you do not control, test it with common software or use a conventional ZIP. Saving a few megabytes is not useful if the recipient cannot open the file.