Most of the paints and a few of the brushes in my toolkit originate from these two kits.

Reaper Miniatures Learn to Paint: Core Skills
Reaper Miniatures Learn to Paint: Layer Up
Brushes:

This contains the brushes from the aforementioned kits, as well as some wider brushes and some fine tipped brushes in various sizes and shapes.
Palettes and Paint Stirrers:

Gotta have somewhere to mix your paints and washes. These are some cheap plastic ones.

Sometimes you need something disposable to mix paints with. I’m using coffee stirrers that I’ve cut into shorter pieces to be more convenient. I probably should switch from wooden ones to plastic ones, since the wood ones soak up a bit of paint and use it up a bit faster, though with the amounts I currently use of any one color blend seem to make it irrelevant for me.
Brush Drying Stand:

This brush stand is for brushes drying during or after I’m painting. The tin catches any potential dripping, the 3D printed piece keeps the brushes from rolling, and the pin is for unclogging paint dropper bottles.
Here’s the stand I printed:
5 Across Paint Brush Holder by jt7125
Paints:

These paints came from the aforementioned kits and a couple of bottles of primer I had to order separately.
WARNING: If you order paints/primers, be aware of temperatures in your area during delivery. If the paints freeze from being left out in freezing temperatures unattended, the primer becomes permanently unusable and you can’t hold the seller or the delivery service liable for ruined product.
Water Cups:

I have three containers of water. One is NEVER dipped in except with a dropper, for thinning paints into washes. The other two are my primary and secondary rinse cups. The primary gets the majority of the paint off, the secondary gets more off (principles of diffusion). I chose the rinse cups the way I did in order to minimize the risk of tipping them over.
Painting Handle:


I’ve seen people using various painting handles and/or bottlecaps for painting their minis without messing up the paint by touching their minis. I printed off one, and a bunch of pucks to swap out minis. I attach miniatures to the pucks with blue-tack, then either paint them on the puck or put the puck on the handle, and I can rotate it with my thumb as necessary.
Base Miniature Holder by Hawk59 on Thingiverse
Lighting:

I wanted lighting from a bunch of different angles without having to keep moving my lamp, so I printed, built, and modified this arch light. I’m probably going to rebuild it once I fix some warping issues with my 3D printer.
LED Bridge Light Mini by FeedMePi on Thingiverse
Base Extender for LED Bridge Light Mini by Ralnarene on Thingiverse
Blotting:

I use a bit of paper towel for blotting/cleaning the brushes. The black paper is for contrast if I’m wiping off light color paints for dry-brushing.
Lighted Magnifiers:

These glasses are worn in front of my regular ones, with lights on each leg to add a little light in the area I’m looking at, while also magnifying details to make things easier. I’ve found these useful for other aspects of my hobbies.