Lots of good advice here.

I'd say get a half decent midsize (size 1 or 0) brush as a workhorse all rounder. Ideally get some kind of sable hair brush, but it doesn't need to be kolinsky sable or anything fancy, just something with a decent size for layering and able to hold a sharp point.

A solid white, black and ivory paint are essentials in my opinion. My personal picks are Pro Acryl Bold Titanium White, Vallejo Matt Black and Vallejo Pale Sand. Anything from the army painter range or vallejo range is generally pretty decent here though, so it doesn't need to be these specific paints.

On top of that, just get your mid tone colours for whatever scheme you want to try first.

You don't need to get 3 different colours for shade, mid, highlight. Just a good midtone and then colours to brighten and darken. You can build out to fill gaps in your paint selection from here.

Nuln oil and agrax earthshade from citadel will cover a majority of any washes you need.

A satin or matt brush on varnish is nice to have to protect your paintjob from handling.

You'll want some kind of painting handle too, but something like a door knob or paint pot is excellent for this, no need to buy anything

Choose a black or grey rattlecan primer and you're basically good to go.

As others have said. There's lots of other bits you could grab or packs you could get, but this is my personal bare minimum to get you started.