I know you said you can code, but I really have to emphasize this. You need to be proficient in Java. If you ask a Java question in a modding discord, you will not get help. Also, use IntelliJ Idea.

I'm assuming you want to use Forge/NeoForge. If you want to use Fabric(-like), I'm afraid I'm a noob in that field, so ignore my reply.

Look at McJty's tutorial series on YouTube. Truthfully, most YouTube tutorials are good enough, except KaupenJoe. He just copy-pastes code. I strongly recommend McJty's, though. Why?

McJty not only has complete tutorials for most modern versions, he has an entire website and GitHub repo with all the code in his example mod. When your code doesn't work, you can compare his with yours side-by-side without needing to pause a pixelated YouTube video.

Before you start coding, join the NeoForge official discord as well as the Modded Minecraft Development discord. Both are great fallback forums for when Google and YouTube don't solve your problem. Just be warned that the NeoForge discord doesn't support older versions. If you're modding a really old version, join the Legacy Minecraft Modding discord and look at their tutorials instead.

Start out by following McJty's tutorial series for your version of choice. Learn how he does things, observe how the Forge API works (it's weird, be warned), and get used to working with Minecraft's infrastructure. Don't just dive into your own mod like I did years ago - you'll lose motivation quickly as you try to juggle learning the API and developing your idea.

Here are some very important out-of-order tips for once you start your own mod:

1. The official Forge docs.. suck. Use the Gemwire wiki if it has docs for your version.
2. If you want to learn how to do something undocumented, search the NeoForge and MMD discords for messages sent by someone with a similar idea. You'll be surprised how unoriginal we all are.
3. Lastly and most importantly: start small! Don't try to make a huge tech mod, RPG overhaul, aesthetic rework... nothing big. Fix some QoL issue you hate in Vanilla, make ruby tools and armor, add a new food and crop. Make something unoriginal, easy, and well-documented so you can get help while you learn.

Once you're confident in your Java and Forge knowledge, start modding!

There's a YouTuber that makes really good beginners tutorials, I think his channel is called "tutorials by kaupenjoe" and he's been doing them for pretty much every recent major version.

https://wiki.mcjty.eu/modding/index.php?title=Main_Page

https://fabricmc.net/wiki/doku.php

You will want to use SpigotMC for the quickest way to get started. You can check out the guides here: https://www.spigotmc.org/wiki/spigot-plugin-development/

If you want to do content mods, I recommend the Fabric modloader. Good tutorials and many great mods were made by more "green" programmers.

Step by step tutorial: https://codakid.com/guide-to-minecraft-modding-with-java/

Tons of sample code: https://github.com/TheGreyGhost/MinecraftByExample

Since you don't know how to code yet, I'd definitely recommend learning some Java basics first. For getting started on modding the videos from Kaupenjoe have been very helpful, when I got started. He always does tutorial series for every major version for both Fabric & Forge/Neoforge. He also has a playlist that teaches you Java basics with some exercises iirc. Good luck! :D

Full Java course on yt (i forgor the author but it's exactly 12hours long)

Kaupenjoe's tutorial series for the version of your choice as a quick rundown of what's possible

Reading source code of other mods for reference on how they implement features similar to what you want to do

Joining some modding discord and asking there for help if you have particular difficulties with something

Additionally Coding with Jonh has short but very well done videos on various Java topics

You could search Java common patterns for a playlist of common Java patterns (i forgor the author, but thumbnails are yellow colored, sorry if that's too vague), their usage and meaning (mostly because Minecraft, Forge and big mods use stuff like Builders, Factories etc.)

Learn Java and pray you don't have whatever dumbass brain cells prevent me from learning how to code.

learn to program first, that’s the biggest mindfuck standing in your way

you already have a goal in mind, so that’s great

KaupenJoe has both intro to Java and intro to modding forge and fabric on YouTube. Best of luck.

See Kaupenjoe on youtube. He has free tutorials on there but also has some paid courses with much more in depth tutorials.

For one, don't use Forge for 1.21.1. Use NeoForge, you're gonna have a better time (unless that's what you're already using and you just wrote Forge instead). Second, make sure your IDE is setup correctly.

If you're using IntelliJ (as you should), install the Minecraft Development plugin. It includes a bunch of utilities, including all kinds of templates for mods and plugins. Now for documentation, you're not gonna find much for Minecraft. Best you can get is Parchment, which will name method parameters correctly but you won't see documentation anywhere other than NeoForge stuff, so for vanilla Minecraft stuff you'll have to ask other people or look into how Minecraft uses them

run into the same problem when returning to modding. I've not touched making mods since the days of Risugami's ModLoader back in Beta 1.4 to Release 1.4 or so. So definitely behind a bit. Back then we had a javadoc that made it pretty obvious what everything in the modloader actually did. I've yet to find such a thing for Forge or Fabric, there's very little documentation for either for some reason.

I'll definitely be following this thread to see what everyone else has to say.

So I am going to say something pretty crazy here but I don't think Java is the issue, the issue is that you don't really know where to start when programming.

While Python doesn't offer things such as interfaces for polymorphism and isn't generally as strict on OOP, moving from one language to the other is usually pretty simple. From Py to Java specifically all you need to understand is static typing and access modifiers, with a sprinkle of interfaces and polymorphisms as well as a general understanding of the boilerplate code Java uses - but these things are rather easy concepts. What you're reallig missing here is experience, confidence and general software architecture knowledge.

The solution to this is just "do it". Give yourself an idea of something to program in Minecraft, break that idea into simple statements and then implement it.

Also, to add my 2 cents, 1.20.1 with neoforge might be the best modern version to use. It's the one everyone else uses basically so it's generally the best documented.

Honestly, just get some development experience under your belt, minecraft isn't exactly technically simple, if you want to start regardless, you're going to be basically bashing your head against a wall because yes, docu in general tends to be somewhat meh at best. Additionally, while i'm not particularly familiar with how the communities around each mod loader are, generally, people aren't super keen on holding someone's hand and basically writing their code for them, so you're not going to find much help there either.

I saw in another post you're using GPT, don't use AI as a beginner, at all, you're basically cutting off your own legs because it's going to be very hard for you to differentiate from it helping you understand and it just doing whatever for you, you're just gonna have to trust me here, it's going to make you a worse developer by far.

I love NeoForge way over Forge. I cracked open their NeoForge.jar in Eclipse and just poked around for a bit, looking at how their mods (and some popular mods like apotheosis and mekanism) work. Their GitHubs are also a good resource