This is the process in which I usually create my art, put as simply as possibly. I usually work on letter (8.5in x 11in) size paper at at least 300ppi in either Photoshop or Clip Studio Paint.
Step 1 - PENCIL:
I draw the initial sketch. I try not to draw too roughly to prevent leaving any pencil markings that'll be difficult to erase when I do step 2.
Digital: I'll draw the pencil sketch on the bottom-most layer.
Step 2 - PEN/VECTOR LINES:
I prefer to use non-smudge pens (MICRON pens of various sizes). Once I'm done I'll erase all the pencil from the paper. I then scan the image onto my computer.
Digital: I then draw pen or vector lines (for nice, clean lines) on a new layer on top of the pencil layer. I'll hide the pencil layer afterwards since it's no longer needed and only used as reference. If I'm adding any monochrome (black and white) patterns, I'll usually add them now as well.
Step 3 - BASIC COLOR:
On the scanned image, I'll change the threshold to make the image strictly black and white (NO grey) before coloring). I'll also need to make all the white
All Digital From Here: I add flat, basic colors onto a new layer beneath the pen, vectors, and pattern layers.
Step 4 - SHADING: I create a new layer directly on top of the basic color layer for the shading. I usually use a darker hue of the basic color that I'm trying to shade over (sometimes I create more then one shading layer, keeping the darkest shade on top).
This is also where I'd add a background layer if I wanted and place it as the bottom-most layer.
Step 5 - HIGHLIGHTING: I create a new layer directly on top of the top-most shading layer for the highlighting. I use a lighter hue of the basic color that I'm trying to highlight over or sometimes just strictly white. Sometimes the highlights have to be on top of the pen/vector layer.
Step 6 - FINAL: In this order: Add my signature digitally (if needed), flatten all layers, add any borders, and apply a blur to the entire image. For printing reasons I have to ensure that the entire image is at least an eighth of an inch away from the edges, or keep in mind that whatever is that close to the edge might be cut off. It's now finished!
An extra tip: I'm very particular when it comes to making sure ALL pixels are covered in the color they need to be or not transparent where they don't need to be. For this reason I work with all of my tools with the anti-alias OFF. Anti-alias creates extra pixels around every pixel placed on the image. It's a great effect for photos and preferable to some but I can't stand it! Having all of my tools set witOUT it allows me to make perfect color-specific selections when I'm trying to shade, add any patterns and textures, etc. The blur I add at the end of finishing my images compensate for the crispness of having anti-alias off.