Detailing first? Don't listen to that :•
Work on the sketches first.
Its te bones of your skeleton (drawing)
Sketch what you want to draw mirror it once to look if it looks ok. Be careful for the lengths of the arms and legs.
If you can handle the sizes and such.
I would suggest to look at some more expression in your characters/ how you want to put them in your drawing (pose) and start playing with the colors and details.
Maybe you seen my art on this website/ banners.
But remember that is just a style of drawing, not many detail and such, don't link those tips to what I drew on this site my tips here is more for traditional art.
Besides that, nice gowing!