I prefer:-
PROTECTION
LOCATION
WATER
FOOD

Protect yourself from any immediate threat (fire, flood, cold, heat, blood loss, injury) Get a shelter up, get out of the wind/rain/sun/whatever. Get a fire going.
Locate. Ascertain where you are. can you get out yourself and/or put up signals, blow your whistle, flash your mirror/light, get a fire going.
Water. Hopefully youre carrying some. If not find some. Find damp ground, vegetation, dry stream bed, fissures in rock, puddles, get a solar still, transpiration bag going, catch rain/dew.
Food (you can last three weeks!) make some traps, eat your Mars bar outta your pocket, put fishing line out, make & bow & arrow (keeps you active & you could shoot a birde/small animal)

In the UK at least, Protection & Location are my biggest priorities, NO shortage of water & if i fell or injured myself in the hills Id concentrate on staying warm, dry & being seen.