I want to start making characters; I need help.

Hello everyone, I've recently posted a project I've made here on this Subreddit, it took me a long time but I was able to pull it off. I have never worked with characters properly so I want to make a scene about a character wearing an armour. My question is, how to start?

Now, the armor is gonna be covering the character from head to toe, so I can just import a basic 3D model and make the armour. However, I don't know how to approach it. I couldn't find tutorials that fit quite the idea I'm trying to achieve. Like I got the model, I started blocking out (or like creating the armour pieces) but how do I place them properly? How do I join them to the body? How can I make the rig control the body and the armour simultaneously? How to texture each face of the object differently rather than having one texture per object?

If any of you are familiar with modelling, you'd know exactly what I'm talking about, so according to your humble experience, what's a good place to start understanding how to approach it and/or good tutorials to follow?

Oh and also, I've been in Blender for a short while now and I keep hearing about retopology, remesh, how to keep your topology in good count and all that, I'd really love to dive into that world at once. By "that world", I mean (re)topology, remesh, keeping low topology. all that.

Thank you very much.