I recently opened a project and realized it was a pleasure maintaining this project and understanding the code because there were meaningful variable names, easy code structures and comments on the right stuff (admittedly that comment thing needs to be refactored). That was my first experience of this kind because I created the project after reading the Book 'Clean Code' from Robert C. Martin. This book inspired me to write ,surprise, clean code. Not the exact way as he tells it but i think i got the point that he wants to tell. Software lives and writing software in the 90's was different than writing software now.
My goal was to write code that's easily maintainable. When writing code, you usually think about the guy who will maintain this is one of your colleagues or else (or you don't think about maintenance in any kind of way). But, if you're bringing a little experience, most of the time it's you maintaining the shit out of a project that was thought to be a one-time-application! You won't get into the source code easily until you use easy to understand variable names, formatting and coding practices the right way.
It can be a long and hard way until you get this to your mind but I realized it's worth ist, learning this asap.
Write code like you're the one who will maintain it.