Home DIY

Dont do it from a ladder!
Even ground floor ones are usually easier from inside.

Actually not as heavy as you'd imagine.

A normal double glazed unit is 20kg per SqM. Add on some for the frame and hardware.
Especially if its a top hung window, you'll have to hold it in place while getting the first couple of screws started when putting it back in.

I found that removing all of the screws from the bottom and leaving one in the top until I had a good grip of the window frame meant that when I unscrewed it then I felt like there's no way i'd drop it.

Good plan if its side hung (a hinge top and bottom on one side)

Top hung (a hinge either side at the top) is more awkward as you need to support the weight more when removing the last screws and more so getting it lined up when refitting.

Wrapping a cargo strap around the sash makes for a useful handle.
Have a couple of screwdrivers on hand as dropping one would be awkward if there's only one screw holding the sash