I have included the core guide (version 3.0) in the mod files page.
The only purpose is to give you something to download if you want to endorse this file.
It doesn't give me a boner when you endorse it, but it will increase the visibility of the guide to people who may need it.
Here's the table of contents so you can see what is covered in a quick glance:

Note:
As of version 3.0, this guide has sufficient information within to cover male head sculpts as well, even though the original guide was written purely for female followers. You can search for "beards" and "orc brows" if you have issues with these parts in general. I will not be rewriting / extending the examples where female body meshes and textures are used; they are pretty much just a 1 for 1 swap with their male counterparts. Big thanks again to SymphiMoose for confirming my theories and processes regarding beard TRI files!



My intention is to make this guide adaptable, fluid and ever-changing through user questions and responses.
As a semi-experienced basic (waifu) follower mod maker, a lot of things come naturally to me for the creation process, so I might need some user feedback to remind me of things that I've forgotten to detail fully because it already comes as second nature.

If you require help, PM me and I will pass you my Discord ID and we should be able to fix things up much faster there.
If you do not have Discord, you can PM me or leave a comment if you are stuck at any specific step. but it is more time-consuming to explain things with images using PM/comments instead of Discord.

I warmly welcome beginners to ask any and all questions, do not feel ashamed or afraid, I don't bite.
For those who would like to challenge the information I have put in the guide, you are more than welcome to do so to.
Just take note that if you start a conversation by saying that any of my advice is 'wrong', I will accept it as a challenge and proceed to use screenshots and video evidence to outright destroy you. I'm just kidding. Or am I? I don't care if English is not your native language, at least learn how to say 'please', and know the difference between 'suggesting' and 'correcting', and I will be nice. Especially if you don't have a single follower mod release under your belt. Conversions don't count.

I have added (an older version of) Charlotte as a NifSkope Repathing exercise in the Files. It's basically an almost complete standalone follower mod, but I left out the last few steps of repathing her head NIF's textures in NifSkope. You can use the file to practice your NifSkope texture pathing.

As of version 2.1, the guide is more or less complete. Mini-tutorials will be added if users request them and I am able to help, but the core of the guide (creating standalone followers with CK and NifSkope) is very much complete. Hope to hear your feedback in the comments section!

Cheers!
Maxiteo

Contributors:
Me (for screenshots, typing, editing, proofreading and providing walkthroughs for everything you've seen in the guide and articles so far)

Suggestion credits (both accidental and intentional):
TheFaceSculptor - for asking about cloning an existing follower for the next release / LOOT section / rework of ESP-FE section
GcodeG61 - how to convert ECE to RM head, low poly to High Poly head (under Articles)
gades28 - changing follower inventory in CK
SymphiMoose - for confirming with me that mismatched beard TRIs leads to freezes

^ Usernames with links have released follower mods with light assistance from this guide, do check them out!

If you would like to check out my resume, click here.