how to analysis chess games?

I have read that one helpful way to improve your game is to analysis your games.But what is the best way to do this ? should i install a chess gui + engine to do this? Or should i do this without computer help? For example would it be helpful to make or use the notes to put down what I was thinking during the game.please comment on what you found useful and why :)

You should first look your game by yourself looking for the moves that went wrong and what you would do different in that situation. If that new situation leads to opponents favor then take back to one move and think from that. do this to the point where you would have won the games. After that you can go and check other moves in your game that are they really good or bad. You should write down your new moves and ideas for those situations and think why you did what you did and didn't do the better move. After that you may take computer assistance and check if your ideas are correct or not. If not then look at the situations and think why you are thinking wrong and try change your way of thinking. If your moves are good when checked with computer then you are halfway of playing better.