Once upon a time there was a usual guy sitting at home. Since he had nothing to do, he was thinking of what he could try out so that he wouldn't be bored. He randomly thought of learning Japanese!
Of course, that guy was me! And actually I am glad that it was me, since now I know what I want to work as in my life. A translator! I was always good at physics and math, but it never gave me the satisfaction like learning English (yes, English is not my mother tongue). I had already done two years of French which were a chaos, but that's a different story, and I had German lessons at school although German wasn't very exciting for me at the time.
The first thing I did was grab a notebook and find a language learning site. I found one called "Duolingo". It's also available as an app. I quickly got addicted to learning Japanese . The site provided me with continuous testing and it involved sound tests as well. I did make my first mistakes too. I downloaded an app called "Jisho" and quickly wrote down loads of Japanese phrases and words. They sadly did not stick into my head so I don't recommend stuffing your head so heavily with grammar. At first the site really did seem very good and I would still recommend it to some, but after a while it got pretty boring.
Then I did a quick Google search for a different site and I came across "Tae Kim's guide to learning Japanese". I did some learning sessions with it and I already felt progress. I also found an app based on this site called "Obenkyo". This is the best app I have found for learning Japanese and I use it every day. I forgot to mention that as someone who doesn't want to spend money, I was interested only in apps that would be for free. "Duolingo" was free to a certain degree and "Obenkyo" is completely free. I was using "Obenkyo" and from it I learned the two phonetic alphabets: Hiragana and Katakana. It was very easy to test yourself in memorizing the symbols and the app even offered tests on stroke order. It has been very helpful to this day.
After a while, when I started to move into learning numbers and some Kanji (the third alphabet of Japanese), I felt a little bit restricted and sort of lonely (if that makes sense). I went and googled for another free Japanese learning site and I found one. It's called "Renshuu". I use it almost every day now since it has a pretty big community and there are TONS of materials for learning that come from different sources of which many are books specially made for learning Japanese. It does have a slight restriction on tests though. You need to pay for a premium version of your account to access other kinds of tests other than flashcard ones. On the "Renshuu" site you can also play games together with the community and the site has a news of their own and that helps a bit too.
https://www.duolingo.com/
http://www.guidetojapanese.org/learn/
https://www.renshuu.org/
I have to say this though: "Thou shall not escape Kanji!" People think that it is possible to learn Japanese by learning some basic Kanji and the two phonetic alphabets, but from what I hear, that is not true!
To make less mistakes in my journey to being fluent in Japanese, I searched Youtube for some Japan related channels and i found some. "Abroad in Japan", "Rachel & Jun", "Texan in Tokyo", "Reina Scully" and "TheAnimeMan" were the first to catch my eye. I definitely recommend their stuff since it helps in learning the culture of Japan and shows you the beautiful places you can visit and delicious foods you can eat there! That's about it for what I, as still being a student of Japanese, did when I started out and I hope you will gain something from this too!