How can I help a friend improve at the game?

I like to play with a friend this guy and I play a lot and we enjoy playing together and hes still needs to learn hes been playing for a year ive been playing for 2 im stuck on what i can do to help him improve I've tried helping him improve his mechanics a while back he ended up doing well but i watched some replays of his and his decision making is not that great, Im trying to help him improve by telling him by saying thing like "hey when someone says you did something bad, try to think if you can improve off that" and many other like "think ahead before going in on a target" hes also very aggressive and he ends up giving a lot of kills because of that Im slowly running out of ideas what what i can do to help him improve I`m looking for ideas to help him
(sorry if post is bad my first post on the boards) thanks in advance