That may work, but I can never for the life of me remember what on earth each flag was for.

Doesn't help that '-a' basically means 'all the flags', meaning you have to know them all to figure out what on earth it's doing. Or just hope it is enough.

For tar, I have memorized: x, c, z, j, v, f

The trick with tar that people seem to have issues with is the ordering with "f" - since it takes an argument, if you're using the combined short form it has to be last with the filename immediately following.

Since a few years I only use dtrx. https://github.com/dtrx-py/dtrx/ I never have to learn this kind of stuff anymore.

Neat. Now do rsync.