Once you reach a certain level, the opening principles like controlling the centre should be drilled into your brain. After that, you'll have to look into more advanced concepts like preventing isolated pawns, preventing weak squares, creating outposts, etc. Here's a video on concepts like these, it helped me a lot.
https://www.youtube.com/watch?v=BYtXMJjqfvw
The way I think about the game is this. The two centre squares are the most important squares in the game, and I want to advance my entire piece set much like an army. I try to build into the centre in an arrow like fashion, and then try to gain a material advantage. If the centre is cluttered I might sacrifice a piece to open up space. If I have an option to take away from the centre or towards I always take towards the centre. I also look for forks and pins, while advancing pawns as far as possible while defended in hopes of advancement. Do i need a coach? Where am I going wrong?