play zero clutter, bgh, or any $$$ map = dun even bother microing. too many units, not that any1 cares about 1 hydra dying out of 10 groups.
limited resources map micro is good. ex. u can use 1g of marines + few medics to kill 4g's of lings, 3 goons kill 6 zealots, 8 zealots kill 8 zealots with all 8 of urs alive, etc.
marines is easiest - micro marines and medics, let medics stand like wall, marine get hit u run, form a natarual deadlock, stim before they come, could pull some scvs to help as wall, etc.
goons VS zealots - pull the goon that is under attack to the back (keep doing it), if did well then the zealots should look like they're chasing your goons while they're getting hit, but none of ur goons should die (will get a couple hits but shouldn't die), just b careful dun get surrounded
8 zealots VS 8 zealots - i think is hardest. u gncountered battle, watch carefully from bottom screen which one getting hit (almost dead), pull him back attack again, look into group, find the one getting hit, pull him back attack again, again and again. at the end if perfectly microed u should have 8 zealots all red/yellow while all of their dead.