I’ve been experimenting with a unique grid paint program called Hexels 2.5 in which you paint with blocks, octagons, and other shapes. It is great for pixel and isometric art. It’s also great for blocking in because it forces you to paint on a grid and this is effective in preventing you from adding details. After I got it blocked in, I imported the painting into Photoshop and painted the details in.
Ref from Wikimedia Commons