Eddie, I'll sum it up here.
Belly colors-Females in good condition have heavy pink bellies. Males are more of yellow but can show a faint shade of pink.
Finnage-Males have more pointed rear end of their dorsal fins.
Black Spots-The small blue spots tend to cover the black spots in females whereas males have them around the black spot.
Size-Males tend to be bigger than the females.
In your lfs tank, males tend to spar while females watch but in some cases, females also tend to spar with each other.
Furthermore, rams these days tend to be less sexually dimorphic with females lacking the pink bellies. And in some cases, there are farmed fish being injected with hormones thus the resulting entire brood are males.