Any good modding guides?

[WereElf]

As a programmer myself, I'd love to be able to make some mods for the game. I even have a few ideas already. Are there any good guides that can help me get into it?
I am mostly planning to do functional mods (for example, I wanna improve how summons and wild shape's HP scales when you're multiclassing). But I'd also like to know how can I do visual mods (like replacing textures, or altering 3d models).