The foundation of Spore modding, SporeModderFX. This useful program allows modders to get into Spore's .package files to edit the embedded subfiles, including .prop, .sfx, and so on.
If you want to get into Spore modding for the first time, this is a good place to start.
If you wish to dive into more complex Spore modding, which includes coding entirely new functionalities, we highly suggest looking into the Spore ModAPI Development Kit.
The go-to wiki for most in-depth documentation on all things Spore modding.
When you first export a Spore model, its multiple meshes in Blender make it difficult to cut or rig properly without hidden edges of parts poking out. Lamyakao has a tutorial on how you can get rid of them using this addon, by Philipp Seifried.
Edit Mode: Select all -> Vertex -> Merge by distance
Edit Mode: P -> seperate by loose parts
Object mode: Select the parts you wanna merge -> N -> Edit -> Massive Boolean (check "sort operands by distance)
(You shouldn't perform the last merging step on the entire model at once, but rather groups of 20-30 parts)
This .zip file contains a SporeModder FX project with two base paints, and thorough comments explaining what each part of the project does. Made by Delta Unit.
Skinpaint mods aren't all that easy to make, especially considering materials and whatnot. However, Delta Unit has done a good job at explaining it all from the ground up.
Based off of ZerbieSlug's own interface mods, this is a more comprehensive way to make GUI mods. While not everything may be covered, what's included in this kit should be enough to make a significant change. That is unless you WANT to make the most obnoxious UI known to humanity.
A tutorial from a rising star in the Spore Modding Community. Go and show him some love and respect if you enjoy his modding progress thus far.
Contains a very bare-bones SporeModderFX project containing all the essential files to make a very simple single part, with in-depth details regarding all the essential properties, what they do, and the best ways to utilise them efficiently.