The most important quality is to spot the inter–relationships between the chess pieces and their functions. We call it tactics. And, as great players have told us - tactics is 90% of the game! ... If young kids are good at tactics, they can improve very quickly...
Learning endgames is like cheating on an exam. You just know you are going to get asked certain questions, but will you have the answers ready? ... Be prepared: one day you are the professor giving lessons, the next day the pupil.
I think the biggest advantage is that youngsters start to enjoy chess as soon as possible! In terms of improving at the game, the earlier you learn, clearly the better your chances of fulfilling your potential, but I don’t think it is ever too late to start.