Dear LEOs,

my education having been sort of patchy (blame it on the teachers, yeah*), I am currently totally confused by the overwhelming amount of different spellings for certain combinations:

cool-down, cooldown and cool down (when used in front of a noun like 'period')
low-temperature, low temperature (when used in front of a noun, such as low-temperature resistance vs. low temperature resistance - LEO has both).

For instance the different locations for entering hyphens in terms like "spin exchange relaxation free" (SERF) differ from no hyphens to hyphens between all words or at any one or two of the spaces.

I have only looked at versions by native speakers.

I would greatly appreciate it, if anyone could provide some(any!) criteria, I feel somewhat lost.