The way I was taught, and the way I teach people is the most important instruction comes last.
This is done beause it is the one that sticks in the mind easiest. In a TMA environment levels are usually critical because of crossing traffic. Therefore I would give a heading first, followed by the level.
On hearing the level, it is immediately selected.
When giving the readback it is then easier and flows better in the cockpit (IMO) because you read what you have set.
Was taught this way to me this way in flying job and later when controlling.
This is also how you give a descent to an altitude from a FL i.e. 'descend to altitude 4000', Londond QNH 1007Mb.' The QNH setting is the one easiest to muck up and is therefore given last so is can be set in the subscale pretty much as it is being given to you.