there are 4 possible targets for cards, and i think each of these group of targets should have an order in whic all of them are done.

cards targeting your starting hex (enlist cards, buffed units, LLOD etc)
these should all be resolved first each turn (else you would not be able to buff new units, airlift them, etc)

cards targeting empty hexes (temporary heroes, airlifts, airborne, landmines
these should be resolved last, and in case of a tie (2 or more players want to use the same hex for a unit drop) all actions on that hex get cancelled.

cards targeting your own units (heals, buffs)

cards targeting enemy units (debuffs mostly, but some buffs can do as well (death march or bezerk for example or bribery).these should be resolved last, but always go on as long as the target is valid (does not have to be in vision anymore thou).

cards targeting any hex (artillary strikes)

if all these effects are done simulaniously in 5 phases at turn start, it is all clear for everyone i think.

this way you know almost every card goes on, only a few debuffs might get cancelled (feedback if the unit is speeded up in the buff phase, or those effects can just stack.