Starcraft is a really complex game. There are so many aspects to it and the way to success is really diffuse. Sometimes you just find yourself playing endless of games without feeling any kind of improvements. Even though playing alot is key, you have to understand what you are doing and why - and learn from your mistakes!
The quickest way is definitely getting guided by someone that’s already been walking down the long road. In Starcraft 2 coaching can be really helpful and save you alot of time. You need to have the correct mindset and have other goals than just winnig. Even if you win, you do not always win, how strange that even may sound. What if your opponent sacrifises his whole army for nothing. Did you win the game? Or did your opponent lose? Feel the difference.