The most common mistake for a beginner - even for some experienced developers - is focusing too much on languages/frameworks rather than solving problems. It's a good thing to be a "Jack of all trades" but keep in mind that it will get you nowhere if you know all languages/frameworks in the world.
Pick a random one, learn to solve problems with it. Believe me, at the beginning it doesn't matter which programming language you are using. They all make sense.
I am not saying it's bad to learn a new language but make sure to focus on how you can use the language to solve some real-life problems.
Remember, programming is not about what language you use. It's about how you think.
Don't just focus on solving a problem and then jumping directly to the next one. Programming is not just a typing statement. you have to understand the programming core skills - the fundamentals. Programming can be a highly competitive industry, so it's advisable to highlight your skills.
Don't be afraid of having a complex solution to a problem. It's true that Simple Is Better Than Complex but usually, complex problems require complex solutions. Just don't make it complicated - make it understandable.
Some people panic when they cannot solve a problem the first time. Don't be like that, even if the deadline is close. Most of the time the solution is around. Otherwise, you can find an alternative that might work. Make sure you understand what you are doing. Most importantly, never ever copy/paste code from StackOverflow without a complete understanding of it.
Things evolve rapidly in programming. So you better focus on continuous learning.
Reading can be a great way to improve yourself and get up to date. It's regular investment in your knowledge portfolio. But you should critically analyze what you read. Do not believe everything.