I don’t use SAI to paint so I don’t really have settings as such – sorry! – but I’ll leave a link below to the brush pack that I use on CSP.
What I do is line-art, cell shading and before I paint over that I like to set a multiply layer of bright yellow/orange on a lowish opacity over the cell colours. It tends to make colours warmer and more saturated, and combined with bright blue/purple on a second multiply layer for the shadows, it makes the picture pop!
Line-art/sketches don’t have to look great as long as they’re clean and have clear shadows and colour control. I pretty much just add a bunch of multiply layers to the cell colours and just paint straight from that. Don’t feel too locked into the original sketch! I just paint straight on top of everything.
The main brush I use to paint with is the flat brush from this wonderful brush pack by MagdaPROski on deviantart – I also use the hairy brush from it for line art. If you don’t have CSP then I totally recommend that you get it, it’s easily on par with photoshop when it comes to digital painting!
Sorry it took me a while to reply to this! I like to ramble and I went into more detail than I thought I would. Hope this helped anyway!
kluskiwszechmocy 