GUIDE
Grammar
Prepare the ground work
Get an overview
Because it's best to learn vocabulary in the context of a sentence, you'll need some basic grammar first.
As I said in the introduction, I recommend not necesseraly learning but at least reading grammar lessons to get used to some concepts like particles and the different conjugations.
It's easier to learn something specific if you're aware of something more general. I say get familiar with all the concepts by reading the content column. Then go back and actually study.
Which Method ?
I want to study with a textbook
I want the best or most popular one.
The most popular textbook is Genki. Althought not perfect, it's probably the most solid. It will get you where you need to go. You can find a lot of ressources for studying, since it's the most popular.
I want something slow and easy.
Japanese from zero is designed for young students or casual learners with a slow pace. If you thought Genki was too hard, you should try this one. You can also check out the youtube channel.
I want to study with a free guide
NHK Easy Japanese
NHK is free and deserve more recognition. Available in multiple languages. Crash course of 48 lessons, 10 min audio "podcast" for each.
Dialogue, skit, lesson, podcast, onomatopia, grammar. Free pdf and audio.
I need somehting more consistent
Imabi is the free resources for that, it goes in depth for each grammar point. Maybe a little too much, and can be overwhelming for beginners.
What about this tae kim guide?
Popular because it's free, it's often recommended.
However in the pursuit of being concise, the guide has mistakes, errors and wrong explanations. Here's a few links about mistakes in the guide: 1, 2, 3, 4.
Still useful of course but NHK and Imabi are better resources that are free as well. If you can pay use Genki ot the dictionary of japanese grammar instead.
I want to study by looking up specific points
A dictionary of ...
Basic, Intermediate, Advanced japanese grammar is the absolute reference. No need for a second choice. Online database here.
A database
Use Bunpro. You can look up any grammar point for free. You can also suscribe (with a fee) and practice grammar with a built-in srs.
Good old google search
Just type "grammar point" and ... the grammar point, you'll find good results. Hi native and language stack exchange are great when it comes to nuances between similar grammar.
Search on reddit will sometimes give you great explanation by users.
I commute a lot. Any apps ?
Anki.
Anki counts as an app ?
I've made a grammar deck. It regroups grammar points thematically, based on Bunpo.
It also compiles Genki, NHK, the dictionary and others with their actual content in the deck.
Recommended over Duolingo, because you shouldn't use Duolingo for japanese anyway.
It's made especially for Asian studies. Each lesson has an introduction for the grammar point. Then practice vocabulary, making sentence, with nice audio and visuals.
You have to pay but there's a lot of content. From N5 to N1. Lessons are short, concise, with examples. Not great to practice I think, but amazing as a reference or quick introduction to a point.