Rampant Green is a constant tug of war. Usually I go for his energy track early and supliment his card plays with the +1 play growth option. Greens presence tracks have way below average energy gain and card plays, both of which make innates harder to use, but Green has amazing Growth options and super low card costs, which make up for what he lacks in the presence track values. This balances out toward the mid-late game where I find I'm able to dump whole hands and secure my innate powers are used.
For Green, my focus with minor powers is looking for A) Elements and B) Cheap cost. I'm not so worried about effect as long as I know I can pound out my entire hand when I need to later in the game.