Set a datum on your walls before doing anything, you’ll also use it for setting floor tiles.
If you’re only going half height, lay the correct amount of courses on the floor to get to your height, and set your datum 360* around the room to this height.
You can also cut a staff to the same length as your tiles up to your datum and mark each course on it, this will double as a quick measuring stick from your setout points.
No need to struggle trying to hold a tape in the air.
It’s all about making life simple with the least amount of effort.