@soft.raincloud777 Thank you so much! Here's some more <3
@000_peanut I love these questions so here are some answers:
1 - I do not use inner shadow onto my shapes, I'd rather paint that stuff myself if I feel it will make my shapes pop, however the inner shadow layer option tends to make things a bit "pillowy". Much more fun to render it accurately, if you can 
2 - I go straight for color. It's much faster, more fun, and easier this way. The greyscale to color method turns it into a tedious slog, and values don't tell the whole story when you're comfortable with shifting hues away from what normally works - grass doesn't have to be green, tree trunks aren't brown, and skin isnt pink. You can go wild, right away! I'll usually start with an approximation of the colors I want, refine it over and over using quick modifications like color adjustments, and finally clean up the result.
3 - Basic round brush. Most of the time it's at maximum hardness, sometimes I'll soften it to blend a transition in specific cases. I use a pretty constant diameter, and pen pressure for opacity/flow. I use this one brush for sketching, line art, and rendering. All in one! Sometimes I'll use specialty brushes for very specific effects, but 99% of the work is done with the basic round.
4 - You will quickly learn shading and coloring by copying and studying the work of your favorite artists. Eventually the recipe will just "click" and you'll know what to do in any circumstance. Make sure to pick up theory from good teachers specializing in color, like Marc Brunet, Sinix, and especially Marco Bucci.
Pleasure, keep at it!
@gregorya Thank you so much!
@mitsuki-youko Thank you so much! - Oh my god you are 100% right! It's gonna bother me every time now 
Those lines were free-handed and I did not pay much attention to them until very late in the process, and here I am paying the price. Oops!
Thanks everyone, here is some further process on the sci-fi girls.
