There are few layers to learning Blender, but before learning, the Main Principle is to do as little as possible to get best possible result, by using tools which blender provides. You dont draw textures on everything by hand, you use procedural textures. You dont make rigs for generic humanoids(and some animals), you use rigging addon. Also, I would say that 12+16 gb ram is required for comfortable usage of blender. You can live with 4 gb, sure, but it will not be comfortable at all, and you might never be able to use sculpting(or using displacement in textures) or make proper renders. Also, nvidia cards work better, and if you have older radeon card, its not supported by newer blender, and 2.93 is the last blender version you can use.
First one, is learning how to do anything, learning interface, hotkeys, etc. Most of it is very simple, and the more you use it, the faster you will do everything. At this point you should just watch a bunch of videos on youtube, I can recommend a few channels, which mention every single button press they do. And its pretty much the only way to learn it. I would say, you need to know how to do simple modelling, adding random primitives, installing generic must-have addons, such as node wrangler, basic understanding how to render something, and basic understanding of shading, aka materials in blender, how to use hdri and basic unwrapping. Additionally, for simple modelling you need to understand why you should use quad topology. At this point after watching videos, you should be able to make a simple house, or a chair, or anything similar, and make materials for it, place a camera. You dont need to understand what you are doing, just copying what you seed others do. You probably should watch a video or two on how to optimize rendering, to save your time, you dont need 256+ samples for test render, 32 will do just fine. I cant help you at this stage, because everything is just learning which buttons to press.
Next is understanding how to do more advanced stuff, like using modifiers for objects, using advanced materials, or even geometry nodes. At this point you should start to understand what you are doing. You should probably start working on a stuff you want to make, however consider it practice, not something you will end up using. I think, you should understand how to make something what you want, instead of just copying some video. You should know what modelling terms mean, like subdivide, rotate, extrude, scale, cut, add object, install the "must have" addons (they ship with blender anyway). And for materials you should understand(just play around with it) what different coordinate systems do (object, generated(aka global), uv) what textures do voronoy, perlin/noise, waves, and what bump, roughness, and displacement means. I am probably forgetting something, but all of it will be adjacent anyway. At this point you should be able to make something like a snake, with proper scales, out of curves or modelled in a couple of minutes. Or maybe use an addon to add a cat rig, model cat around it, and cover it with hair, with procedural shading. (Or naked cat, if your pc cant handle fur). And maybe even animate it. You should use core principle of "do less" and use addon to get armature with premade animation, use automatic weights and make whole animation in just a minute or two.
At this point you should notice parts which your pc cant handle. Mine for example cant render volumes anymore, due to "fuck radeon cards, their drivers suck", and some other stuff. There are often ways to sidestep it, but sometimes, if you dont have enough ram, for example, there is pretty much nothing you can do to sidestep it. I would say you should be able to at least render a model with 300k vertexes, a couple of materials with varied roughness, metallic parts, bump map, hdri + a couple of lamps. I would say it is the bare minimum of using blender for gamedev. You might consider translucent/transparent/glass materials, but honestly they are not important. Requirements are lower for eevee rendering engine, and it is faster, but you likely will need cycles. I would say you should be able to make "test" renders in a minute, with low sample rate, otherwise everything will take too much time.
Anyway, at this point you should probably think about making something cool via tools you are provided. Probably something based on procedural textures. For example picrelated is a model for a well, and procedural texture for it, it might look complex at first glance, but in reality its quite simple, and only uses a couple of procedural textures and some math. And model is just a cylinder. And lamp uses same model as a bucket, just with a couple of modifiers.
Same with orange galaxy-like splash. Its just some camera tricks, and a couple of procedural textures mixed. Doing something like this is really not necessary for gamedev, but it is fun and educational.
At this point you should start thinking about making game-ready models and exporting them to your engine. Be it 2d sprites (with that I can help a lot) or 3d models with their textures (with that I can help a little). And you should look through cc0 websites with textures, models, etc, like
https://polyhaven.com/ ). For example you can spend a day trying to model a tree, or you can use an addon to generate a tree in a minute.
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