I use Photoshop CS2. Bc I didn't wanna bother torrenting a newer one when I got my laptop lmao
For stuff I do line art on, I just use the plain old round brush and mess around with the dynamics. But if I add any painterly elements I use all sorts of brushes.
Like I looove using wet edges on my brushes when I paint. I especially like using it on things that have a more rocky texture.
For human skin/hair, I use a default brush (but not the round one). It's one of the painter brushes below the airbrushes. I find it works way better. Especially if I compare the way the skin looks on this picture, versus this one which used a round brush.
I suck at clothing so every painting is different bc I'm basically just going "UHH??? HOW DO I-"
But I'm not one of those people who gets too fancy about brushes. Other than a couple textures and some space brushes, I don't have many outside of the default.
As for layers, I generally use ~3 when painting. 1 for the bg, 1 per figure (or sometimes just the entire foreground), and 1 for filters. I find it easier than having a million layers, but honestly I should use more lol. I even use just one layer for colors when I do line-art pieces.
I'm so used to photoshop, I haven't really thought abt moving on from it. I've been using it for ~6 years now? I used SAI for a while alongside it, but eventually stopped using it. SAI was just too different in terms of set up for me to get into the flow of using.

I generally use Manga Studio which... has an awkward name but I sort of find it to be an ideal cross between SAI and Photoshop??
Although, sometimes I go back to SAI if I want to use the binary tool,

Biscuit
I download most of my brushes from Deviantart! They're generally made by other artists and you have freedom do a lot with them. (Most don't even require credit! Which is nice bc I often forget who makes what brushes. )

Biscuit
No problem! Also, depending on which photoshop you use, you might have to import them into your PS, or just click on the file and it will automatically add itself into photoshop.

I use almost always just SAI, it's my love. My tools though don't look anything like the original, I've both downloaded and made new textures and elemaps, and replaced most of the original tools with my own. Out of the 17 tools I use most regularly, 10 are brushes that make all different kind of messy look xD (some for big areas, some for sketching and lines (and kind of cross-hatching I guess), some for little details and so on)
I tend to lay the first "layer" of "virtual paint" on many layers, taking advance on layer modes and such, but as performance of my computer is not that great, I merge all the layers before I start the actual painting and finish it with minimal amount of layers: one is the original merged, 1-2 for the major painting work, and possibly few extras for effects.
As the brushes with texture look better with a big canvas, I try to make it as big as possible, but again the performance of my computer limits me :I

I use Mischief because I hate everything else.

i use firealpaca for nearly all of my art. i like the fact that its free, and the default pens are very sharp and smooth. its a bit like paint tool sai (which i use for effects and overlay) but just the core elements you need. you can also switch the anti aliasing on and off with the regular pens so you can paint and draw with a pixel brush! much better than sai imo.
i just use the default brushes, with my lineart pen size set to 4. i think its an awesome program and very easy to learn and use ^_^
ps: sometimes i use texture brushes, i just import the images from the already existing sai textures heheh