Banana boxes

Three pieces of advice for moving:

They are sturdier than any other box I’ve tried.
They are light enough to hold, even when full of books.
You can stack them to 6 levels safely.
They’re free! Available by the dozens at the nearest supermarket in most countries.

Heavy-duty bags

Clothes need less protection than rigid objects; banana boxes are overkill. But they need a container to hold them together and protect them from dust and smudges.
Regular trash bags tear too easily.
~100 μm thick heavy-duty bags like these are the best option I’ve found.

The common method is to write the content on each box/bag, but little info fits that way.
Labeling all sides lets you identify items from any side. But writing the content to all sides is impractical.
As a solution, I number all boxes and bags.
I use a Google Sheet for a number → content association. It’s surprisingly low effort and high value. And you can easily read and write the spreadsheet from any device, even from multiple devices in parallel if you’re packing/unpacking together with others.