Richard Reti in "Masters of the Chessboard" advises beginners and amateurs to play open games exclusively (if possible of course) by which he means Double KP Openings as White and Black. He recommends learning open games prior to playing semi-open games (Single KP and Double QP Openings - in general) and saving closed games (Single QP Openings such as the KID) for last.
After looking at your profile I highly recommend following his advice as much as possible. Trying to learn the KID ahead of Double QP Openings such as QGA, QGD, London System etc is like trying to learn trigonometry and calculus ahead of arithmetic, geometry and algebra.
What are the pros and cons of playing Queens Gambit Declined as opposed to the Kings Indian Defense as black and vice versa? Thanks