Paintstorm is an amazing program and I want to contribute something to the community as a thank you to the developer. Here are some of my favorite painterly custom brushes, I think you'll like them.
Download: https://www.dropbox.com/s/n242whno2iyna ... ushes?dl=0
I use the All-Purpose one for 90% of the time, it blends and shapes well. The Color Mixer blends hues rather than smudging and is useful for more better onscreen color mixing, it's great for very light mixing then picking colors for other brushes. One or two of the more complex brushes get laggy on large brush sizes (<400), but look great when used lightly. Feel free to play around with the settings and discover your own favorites.
If you want to make your own brushes, here are the textures I use. Many of them are extremely high resolution and will make great painterly effects. If you are using an iPad, DO NOT download them onto your iPad image folder, the file type will change and they will be unrecognizable by Paintstorm. Simply import them directly from Dropbox onto your iCloud drive, then import them from there into Paintstorm via the "Texture" cogwheel option under Brush settings. Have fun!
https://www.dropbox.com/sh/aemminzuqa9c ... vV_Ga?dl=0