when you say rendering what do you mean? and i downloaded a few cool brushes i tend to use a lot, https://conceptartempire.com/paint-.....l-sai-brushes/ from here (tbh i would ignore the textures, good brush work can imply them but theyre fun to play with)
what settings do you use? for me, i just use the acrylic brush with "blend" pressure checked in advanced settings and it works for the look i want. also bigger brush sizes tend to be easier to work with, like say you want to cover a character's body in shadow, a 300 size brush would cover it on a mask layer. i dont tend to mess with the blending or dilution sliders but thats just me.

1) Render, how I define generic unstylised 'realism'
2) I use 2 blending acrylic markers, one that adds colour and one that blends it. It might be a good setup but I'm, like, mega incompetent and I harness the skill of a 5 year old holding the paintbrush in a fist and scraping it on their page, bristles splayed like a frilled lizard all done up for a 70s punk styled disco.
I guess I don't deviate much with bigger brushes but I imagine that works best with specific minimum size settings?
3) You can download brushes???

hmm im not sure what you want to improve on then. like, if you want to do lineless painting i find just studying artists you like is better than reading theory. pay attention to how they define shapes, and look out for edges/unblended brush strokes. as for your comment on bold colors, really it just comes down to making yourself use contrast. you have a base thats really light? crank your next color down near black and shade it, if its too much lighten the value and try again. just make sure to zoom out a lot to see if you can make out the difference in value, good advice i heard recently is to never zoom in more than 100% unless you do lots of detail work. i also find, you can use the shape of your brush to make outlines/define planes on a character without penned lines. the default mid_flat brush i have on sai is one of my favorites for that.

anyway yeah downloading brushes is super easy, idr if theres a tutorial on that site but you can just google it. like, most art programs have this feature, you could even make your own!

Fair enough, I knew the answer would boil down to my own willingness to make an effort to understand. You've given me a few good tips to help me at least deviate from my usual attempts though, thank you very much! I will also have to have a looksee at those brushes too, see if any of those really get the paint pumping.
<3!

glad i could help! <3

Hello! I know this is old but I'm willing to help out

aw sweet! it may have been 11 good months but I still struggle with my painting skills, hehe!

Painting is always hard and confusing when you're first starting but it gets easier one you get the hang of it =D

I recomend you using flat brushes for laying color,this will give you a variety of colors to pick and mix with. And focus on only adding 3 light sources at most (main lighting, hard shadows and bounce lights)

-start with a slightly darker color than the one you want for base and build from there, lay all your colors roughly, don't stress about the details when you start
-go ahead an lay your hard shadows first, this will help you get a general idea of where you want the lighting to go
-Add your lighting, don't go overboard with it, otherwise you won't have enough value contrast
-Bounce lights are lifesavers, they automatically make anything look good. Just lay a contrasting color, or the same color as your background on the edges opposite to your main light source.
-Once you have all of these laid down you're ready to paint and start defining shapes from there!

Additional tips:
-Try to not add any more colors than the ones you first laid down, so go as crazy as you want when you get started. you'll have all the hues and shades you need by blending the colors you first laid.
-Don't focus on details early on, see it as if you were sculpting, start with a rough shape and start building detail, first on big chunk and on smaller details every time.
-If you need to texture always use brushes! you can make you own by playing with your basic brush settings or downloading textures from google images and turning them into brushes. Always have one in handy for different needs
-If you need to texture fur a very easy way to do a brush is to draw small black dots on transparent layer of separate canvas, save it as a brush and make sure you can apply pressure to it, you can play with the settings and size until you feel comfortable with it!
-Study a lot, specially lighting and textures and how light interacts with different materials, 70% of a succesful painting depends on making objects look believable.

I am by no means expert on the matter, but I hope that these handy tips I learned over the years can be helpful to you