How to invade?

Hi, im a low elo Gwen jungle main and the champ is currently good for early invade but idk how Im not good ar the game so it might sounds dumb but HOW do you invade ?

When i know the ennemy jungler started red, I do my red then invade his blue side and recall But then he just invade my jungle too, so whats the point ? Should I go back to my jungle before recalling ? Just steal his buff but not waste Time on other camp?