Everything I'd tell you for free.
No gated downloads, no email wall. If you read all of this and never book anything, that's a good outcome — you'd know more than most people who spend hundreds a year guessing.
Start here
The three that clear up the most confusion
They're not the same thing, most people have the second one, and the products for each are opposites.

Thinnest to thickest, with three exceptions worth knowing.

Longer than anyone selling it wants to tell you. Real timelines, by concern.
Concerns
What's happening, and why
One means it's working and one means stop. How to tell in week three.

Usually a barrier problem before it's anything else.

It didn't. The air changed.
Ingredients
Plain language, no hype
What it does, what it doesn't, and the percentage that matters.

A six-week schedule, and what week three feels like.

Usually no. Here's the short list of situations where that changes.
Or skip the reading and let me look at it.
Fourteen questions, about two minutes, and a plan written for your skin.
Start the assessment