Prioritization is about removing things from a list - not putting them in.
The above is very easy to approve of until one is faced with the actual task of removing something.
I have a trick that seems simple enough to work. I have used it with a customer and gotten to know things he didn't know himself. I use it on myself and get wiser every time.
Take this list with "all things" and separate it to three piles of equal size. Prio 1, 2 and 3. If three piles is too hard, try 9; but do keep them of equal in size.
This is hard to do and the result is not the final prioritization but it gets blood to the brain and forces the synapses to fire in new patterns. To remove things.
I do not tell the customer but know myself that the lowest third in the list will never be done due to money, time or -best of all- the very requirement disappears.