how can we strengthen and activate our lats more ?

In our facility we find that a lot of girls lack from lat activation. Is there any ques or exercises that we should be doing more of?

Make sure the elbows are stable; pointing in the same direction throughout the range of motion of basic upper body exercises.

Alexander Egebak said:

Make sure the elbows are stable; pointing in the same direction throughout the range of motion of basic upper body exercises.

Adding to Alexander's post quoted above:

External rotation of the upper arm helps with a lot of pushing or pulling motions.

why would external rotation of the humerus help alot with pushing and pulling exercises? 

it stabilizes the humerus in the back of the shoulder socket, if memory serves correctly.