Learning Japanese is a very challenging process but there are many ways to improve and be able to communicate with it. Here are some resources that i've used and i'm still using.
FIRST STEP:
Japanese has three types of characters: Hiragana, Katakana, and Kanji. Hiragana ひらがな and Katakana カタカナ are phonetic symbols, each representing one syllable. Kanjis 漢字 are ideograms, each standing for certain meaning.
My first recommendation is to learn hiragana and katakanaand get familiar with Kanjis. There are many good resources to do so:
1) Doriru children book
A japanese friend of mine gave me this ressource and it was a great starter to write kanjis. Repetition is usually a good way to get comfortable with Kanjis! It's definitely my weak spot in japanese, but i was able to recognise basic kanjis better.
2) Obenkyo app
Talking aboout repetition, i've used Obenkyo app a lot on transportation or during breaks and it was extremely helpulf. Also the app is free!
BEGINNER
After getting familiarized with beginner vocabulary and how the language sounds, it is good to have a fairly good understanding of the basic grammar.
Knowing vocabulary is like owning legos : when you discover a new lego, you still need to see it in a structure as to know how the legos are assembled in a natural way! For instance; in japanese the lego for the verb usually goes at the end of the sentence ! The more sentence building structure and grammar you know, the easier you get to use the legos properly (rather than having a bucket full of legos you don't know how to assemble) !
1) Minna no nihongo
A good starter for those who like to have a paper support document and get basic knowledges of the japanese language.
2) Genki
Same intent as minna no nihon and both books looked the same size to me.
I noticed that minna no nihongo had more chapter though andgenki feature more images.
3) For french speakers : Kanji link
Ce site était super intéressant pour commencer, notamment pour la conjugaison et la grammaire de base !
INTERMEDIATE
Now you've been through the basics and you've reached a level where you can understand fairly simple conversations and writings. Here are the resources i've used to climb up on the learning ladder:
1) Tae Kim guide to learning Japanese
This website has extensive lessons with great examples to grasp some intermediate concepts of japanese and I recommend it strongly.
2) Nihongo so-matome
Although the book is prepared for those willing to take the JLPT (Japnase Language ProficiencyTest), I highly recommend it for grammar points, great examples and exercizes.
3) Youtube channels
Miku real japanese:
Real conversations through interviews as well as grammar points explained with Miku !
Kemushi-chan
From her early videos on how to learn japanese, to her latest traveling serie in Japan, i recommend Kemushi chan channel to every lover of japanese and Japan !
3) Language learning partners or tutors:
A language has to be used: my best advice is to find somebody to practice with !