Advice Needed: How Should I Approach Textures for My Mod?

I’m making a mod and I’ve decided that all my textures will follow the vanilla-like style to keep everything consistent with Minecraft’s look. I’d like some advice on how to approach this with the items I have added. I want the mod to look polished and natural to the game, I am going to include Images into this too so you don't need to go into the mod it's self; so any feedback or examples would be awesome. Thanks!

Here is the mod, unofficial-addons-mod