I made many mistakes when first studying Japanese.

But the biggest one, by far:

Not Letting the Language Be Ambiguous

Languages are full of nuance and shades of meaning.

But I wanted to know the exact meanings from the start.

Why do kanji have so many different readings? What's the difference between this word and this other similar word? Is this all useful? Do Japanese speakers really say this?

All these questions would slow me down, making it harder to create a foundation of knowledge I could add nuance to later.

I did learn to accept that some things are beyond my current level. I realized that this search for clarity was taking too much time, so I kind of gave up. But it worked. I can't remember what caused me so much confusion in the beginning now.

But it's worth pointing out that this mistake is more than just a language-learning problem.

Ambiguity can be scary, and doing the wrong thing for hours or even years can feel like a waste of time.

Language learning takes thousands of hours, so there's plenty of time to fix our mistakes.

This is why I tell everyone to see their mistakes (and "failures") as necessary steps along the path.

Let things not make sense, and make as many mistakes as you can.