I believe you know that languages belong to different language families, that is to say, language learning in the same language family has rules to follow. Personally, I have never reported to class, but I have attended training courses. My advice to you is that if you have enough time, you can make plans and strategies based on your experience in learning a foreign language online, and you can completely conquer this foreign language. This kind of study can expand thinking, exercise self-study ability and strengthen academic qualifications, with endless benefits. If the time for postgraduate entrance examination or grading examination is relatively short, then you can be advised to apply for classes and choose a good training institution. With expert guidance, you will save a lot of energy. You should study harder. The teaching materials of training institutions are as unimportant as those of schools, and the knowledge points are the same. I have read three sets of Japanese textbooks, and this is my general experience. Just study hard with the teacher. This training course will consider the classification of junior and advanced levels. No matter what textbooks are used, they should be from elementary to advanced. It depends on which level you choose to apply for. As long as you master Chinese and English well, you don't have to worry about the second language problems of Sino-Tibetan and Indo-European. Remember that quantitative change leads to qualitative change. If you use the right method, stick to it and study hard, you will certainly gain something and benefit a lot!