RiichiBooks VS mjai-reviewer

As for learning, there's Riichi Book I by Daina Chiba here, which I think focuses on EMA Riichi Mahjong, so uses the european terminology borrowed from Chinese mahjong (so pung=pon, chow=chi, kong=kon, etc), but is otherwise the same game. And the Riichi Wiki here.

The best place to start imo is to brush up on fundamentals. Riichi book 1, found free here: https://dainachiba.github.io/RiichiBooks/ has a lot of good fundamentals to look out for. Focus on 5 block theory, defense, and tile efficiency if it's too overwhelming to start!

This might be overkill, but I learned a lot from this: https://dainachiba.github.io/RiichiBooks/ Basically a Riichi mahjong textbook. Section 8.2 sounds like what you're looking for at the moment.

Another important thing is to have better tile efficiency. For a good beginner/ intermediate introduction to defence and tile efficiency, read Riichi Book 1, or as the community calls it, the Riichi Mahjong Bible

The often recommended Riichi Book 1 has a section on reading and defending against open hands that is worth looking at.

Here's Riichi Book 1: https://dainachiba.github.io/RiichiBooks/

Chapter 8 of Riichi Book 1 (available for free here) does a great job of explaining the fundamentals of defence. Then to directly practice you can use Erzzy's folding trainer and it corresponds directly to the levels of safety described in riichi book 1 (this is a link to her efficiency trainer, but a folding trainer is available within the same thing once you run it). For people that don't speak Japanese, riichi book 1 is the go to answer for learning any of the fundamentals of the game :) .

You can also take a look at the defense judgement section of riichi book 1.

There is this website that can analyse your games here. https://mjai.ekyu.moe

This site is pretty helpful in analyzing your games using an AI mahjong program: https://mjai.ekyu.moe/

You can use Akochan to review your games. It isn't perfect and it doesn't give you a reason why your choice is not the best like a chess engine.

There are plenty of things you can do on your own to become a better mahjong player, though. Log review your games with an AI like Mortal or Naga, or with stronger players. There are also a couple of English translated higher level resources for improving your mahjong gameplay, like Uzaku's guide to tile efficiency and WWYD problem books, and Statistical Mahjong Strategy.

This would be an interesting one to run through Mortal.

This is all just what I would do though. If you want a more definitive answer you can throw your game log in to an AI like Mortal or akochan and they'll tell you how strongly they feel about a riichi.

https://mjai.ekyu.moe/ hope this gonna be useful for you

There is a website that can analyse your games and give you what should be discarded based on EV, but its currently under maintenance (https://mjai.ekyu.moe/), if you don't want to wait for it get off maintenance you can just download the program to analyse your games but its not very user friendly: https://github.com/Equim-chan/mjai-reviewer