Gloom and Doom was the first proper game I worked on, so I definitely made a lot of mistakes as a first-time game developer. And one of the first things I would change if I were to go back in time? I’d draw the main characters last.
It’s totally understandable that you’d be super excited to design the main characters and draw the sprites or model them first, but hear me out:
I used Photoshop to draw the sprites in Gloom and Doom. I would have a layer for the rough sketches, a layer for the finished linework, a layer for the gray scale shading and then individual layers for the various colors.

Then a few characters later, I realized it made it difficult to do different clothing variations. So I changed the way I used my layers, like adding the solid blacks to another layer, and separating the basic inking and the fine details into separate layers so I can quickly block colors.
Additional improvements to the work flow came into play when I had to add new facial expressions. Basically, the most minor supporting characters (aka the ones I drew last) ended up having the most advanced and neatest workflows.

But the main characters are the ones who need the most expressions and variations, especially when creativity strikes while programming and writing. Ironically, they are now the most unwieldy Photoshop files to make changes on with messy layers.
It made me dread adding new changes later. Messy stop-gap fixes would only make things worse if more additions would be required after this round of changes.
Furthermore, my drawing had also improved a fair bit so Gloom’s robes look like crap compared to Joh’teolath’s clothes, and Muriel’s wings look more feathery than Michael’s even though he has so much more screen time.

Tl;dr
So yeah, my advice is for beginner artists to rein in your excitement and finish the minor characters before the heroes. By all means do the concept sketches of your mains first, but get your skills and workflow in place before working on the important characters.
You’ll be thankful for it later.
