Mistakes are inevitable in all areas of life, especially in languages. Nevertheless, most people try their hardest to avoid them. However, I have a little bit of a different philosophy for you. Instead of avoiding making mistakes entirely, I encourage you to learn to understand them in good time and to fix them as purposefully as you can.
Four critical mistakes
Completely ignoring pronunciation
Even if you plan on using a language only for writing, knowing how to correctly pronounce its words helps with listening comprehension, vocabulary memorization and speaking fluency. You simply can't feel comfortable speaking Spanish with English sounds; that's why we pronounce our sounds differently.
By ignoring pronunciation, you can get yourself into a situation in which you are able to put words together perfectly, even whole sentences, and still not manage to get your point across during a conversation. Similarly, even while consistently doing your best to use high level vocabulary, you could still find yourself being frowned upon or not understood by natives. Furthermore, you could have trouble recognizing words when listening, resulting in you losing confidence.
Studying irrelevant vocabulary
Memorizing new words requires a lot of effort, which is why learning any word can deplete your energy levels in a matter of days when tackling a new language. You have to find out what terms you need, which ones you will actually use, and accept your limitations as a human being. You don't have to know every word. In fact, you can't.
The sooner you accept this idea, the happier you will be.
You may be able to pass a test on animal or plant names by memorizing specialized vocabulary lists; you may even score 0.1 higher in a general test. However, in a real-life situation, the value of knowing these pieces of information is close to zero.
Essentially, you could know literally thousands of words, yet still not understand the most basic sentence. This leads to frustration and failed learning. Even if you only learn fairly useless words on a small scale, you will still be missing out on potentially useful vocabulary. You can do a lot better; help yourself and filter what you study.
Running away from difficulties
People often ignore tough topics and try to keep on learning a language without tackling that one important piece of knowledge (such as a difficult verb tense). This gets them stuck in a kind of never-ending intermediate level.
Whenever you come across a problem, write it down. When you find some spare time, learn about it and try to sort it out. If you can't, ask someone who knows more than you. And finally, if you can't find anyone, just keep it alive in your mind. You will learn more about the topic as you progress, and you will most likely be able to solve it someday.
Your progress can be sabotaged, or at least hampered, by ignoring certain difficult subjects, especially those that represent important features of the language (German declension is a good example).
Understanding said difficult subjects will allow you to progress faster and learn the language better and more deeply. Frustration over a specific topic can also produce mental blocks when thinking and speaking.
Using resources poorly
There is no valid reason to stick with your old teacher or academy if you don't feel that you are progressing after every single lesson. If something becomes a chore rather than a passion, or if you wish you’d spent your money on a new game or a tasty meal instead, just let it go.
You need to start looking for someone who will truly inspire you and with whom you savor the pleasure of learning. It may take one day, two months or three years to find the perfect teacher, but it's necessary to take action if you find yourself stuck in a boring routine and wasting your money.
After all, there is no need to rush. Remember that learning a language incorrectly can be significantly more harmful in the mid and long-term than just waiting.
Wasting resources is emotionally difficult and can even have an impact on other areas of your life. It may prevent you from learning, cause you to give up or make you a more pessimistic person. Assess your resources exactly as you would if you were playing chess: strategically.
How to move on
Try to have your own language learning agenda. Going through a grammar book or doing a course are both fantastic ideas, but you must never forget that these are simply tools to achieve your goals. Try to combine different learning methods until you find a routine that you like and that makes you feel that you are progressing. Try making lessons shorter or longer, studying earlier or later, reading and practicing more or less often. In short, do whatever it takes to stay passionate.
Of course, finding the right teacher is critical to this goal. Someone who is aware of all the issues involved in language learning will certainly be much more efficient than just any regular native speaker. In addition, you need to make sure that they have a professional attitude, that you genuinely enjoy talking to them and that they have a good Internet connection.
The teacher you choose, the way they sound, the pen you write with, the time you devote to learning, the word lists you create... all of these contribute to your learning and will determine how fast you grow as a language learner.
I wish you the best of luck in this adventure!
For those learning Spanish
I am a native Spanish teacher and I always teach my students using the above mentioned philosophy. I love learning as much as I love languages, and I consider myself to be thorough, methodical and committed. If the ideas I have mentioned previously speak to you and if you truly value learning, I will be more than happy to meet with you.