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https://github.com/adnzzzzZ/blog is good with plenty of advices on how to structure your game code by a guy that actually released a good game

This book is pretty good (and free as a web version): http://www.gameprogrammingpatterns.com/

Some guy said that using patterns is an anti-pattern.

Quality of the game has very little to do with quality of the code. Famously, Minecraft's code is a huge mess, Microsoft had to rewrite the entire thing in C++. If your objective is making a fun game, you should focus on that, and do away with actual programming - most games don't require implementing some clever solutions, tweaking existing basic logic gets the job done. Some people focus on making technically impressive games, with thousands of live interacting objects - then good programming is essential.

The bottomline is, don't stress yourself too much over the quality of your code - as long as it works, it's fine.