Pako writes in his comment here that we should avoid making mistakes in our English learning. He also encourages English learners to spend more effort on input rather than on output, and on that point I do agree. The more you prepare yourself with a lot work on your own, listening, reading, and learning words and phrases, the better you will do when you try to express yourself.
However, you will still make mistakes and should not worry about it. I say that because there are aspects of the new language, structures, phrases, words etc., that you will not get right until “it clicks” in your brain. You can read, you can study the rules, you can practice….. and you will still get them wrong quite often. Eventually, with enough work, however, the correct way of speaking will become natural, but it will on your brain’s timetable. You can control your effort and how you study. You cannot control how quickly the brain will develop the right kind of neural network to make these new forms of expression natural. If you stay with it, though, it will come.
It does not matter how many times I look at verb conjugations or noun declensions in Spanish or German, or how often I try to remember which nouns are masculine or feminine, or how often I read that a word in Mandarin is third tone or fourth tone, I will continue to make mistakes for a long time and only improve gradually.
It is hard for me to get used to saying these things correctly, even though I understand the concepts. It is like Chinese people always getting “he” and “she” wrong , even after they are quite fluent in English. It is not because they do not understand the difference. In language learning we need to develop the ability to do “naturally” something that is not “natural”. This takes time. It requires us to create new abilities in our brain.Some aspects of the language are learned faster than others. In many ways these things are outside of our control.
In meantime the learner needs to communicate, to use the language, to enjoy communicating and to improve his or her feel. Worrying about making mistakes is not productive. I sense that Pako does not disagree with this and that much of his argumentation amounts to splitting hairs. Yes we need input. But surely we are not to prevent learners from communicating until they are error free and totally fluent!