When I first started studying Japanese in high school me and a few friends would go online to sites like Japanese-online.com and try to study different phrases, sentences and structures etc. needless to say we didn’t get very far. Not because of the website but because we were impatient, plus we had a ton of other school related things to do.
I continued to study bits here and there till college when I was able to take some Japanese classes at a language learning institute. The classes were great, my teacher was kind and patient, I also met some very nice people. However I felt that the classes went through lessons to slowly and were going to be to expensive in the long run. This is what lend me to figure out a good way for me to self study. Self study allows me to go as fast or slow as I want when learning, its free which is a major plus for me and I can control how I learn. There are also many resources available online now like Italki/ lang-8 that you don’t really have to study alone.
To be successful at self studying you really need to build a routine for yourself that you can stick to.You also have to be a good self starter, if its hard for you to get started on something and stick to it without any oversight then self study may not be for you, which is not a bad thing. When I was preparing for the N5 I studied 2 to 3 hours a day, broken up into 30 minute sections through out the day. First hiragana/katakana practice using Anki flashcards, followed by kanji practice using flashcards that I made myself. After I did listening comprehension, by watching Japanese youtubers or watching keyhole TV. Lastly I did 30 minutes of a new lesson or reading comprehension, I studied a new lesson every other day. Then at night I would write an entry on lang-8 to be corrected. Nowadays I’m definitely not as hardcore, but wanted to give you an idea. I only study for about and hour a day now. I study kana and kanji everyday and grammar and vocab later on. I also play some Japanese games but I dont count that in my hour of study.
It really doesn’t matter whether you chose self study or language classes as long as your happy with how your learning and your having fun doing it. If self study is a chore and painfully boring for you then try some classes, which were pretty fun and lively for me. If lessons are just way to slow for you or too expensive and you really have no problem learning on your own then try self study! Either way ganbatte!