>>126432672It depends on the situation. Generally, if the character is dominant in the panel, then I'll draw them first. But if the background is more important, I'll do that first.
In this example, showing off the scene was the focus, so I figured out the perspective for the bed first. Then I drew boxes for where I wanted the characters to go to help guide me on how the character's anatomy would look from that angle.
If the situation was the character was interacting with the background, making them equally important, then I would figure out what would be the most difficult thing to draw. If I envision the background would be more difficult to figure out, then I'd draw that first and it'd be easier to fit the character into that spot, and vice versa.