So I guess you learn something every day. I though I could gather some of my observations and little theoretical things here. Some things will be theoretical, some things will be crazy basic, I just got glasses and I see the world for the first time. 
(No kidding, I have been an illustrator for 15 years though.)
My random thread of observations.
Alice
#1
Alice
#2
We tend to see the world through a lens more and more and therefor, we get a perception of reality from the images we see. It is tempting to use a depth of field effect to skip background details and highlight the main focus, but it is often done by the expense of the authenticity of the picture. You feel like your are looking at a picture, a painted photo, not a painted reality. By using atmosphere, fog, light etc. as a reducer of details instead one can circumvent that feeling.
Alice
#3
Adding a pen loop meant for calendars to your ipad is a nifty way to keep track of your apple pencil. Just make sure the loop has no glue residue at the inside of the loop.
Alice
#4
On the topic of Ipad pro and apple Pencil. So far, one of the best apps to paint in is Procreate. They have a real nice and streamlined function for recording when you paint. Maybe not the first choice when making complex tutorials, but a nice addition to see the process.
Lunatique
#5
Infinite Painter is another art app you can check out. It contains some tools that Procreate doesn’t have, and has similar level of brush customization.
Alice
#6
Will try it!
The app paintstorm has a really nifty mixer palette, im not quite sure I like the rest of the app yet though
Alice
#7
Using oil pastelinstead of pencil to transfer sketches will leave you with a clean sketch that will dissolve into your painting instead of bleeding through.