I think this is the last one. Also this one is going to be way less than what I had planned since I no longer have access to the original files. But first thing's first! A little goes a long way:
Gradients and textures take like ten seconds to apply and are always a simple improvement on an otherwise bland panel! Unless they need more careful and selective usage. Which plenty do-- most vegetation type textures in general don't work unless you're careful about using them. But if your garden arts aren't working then honestly that means you just need to not do a garden in a comic until you've learned how, because instead of one garden it'll be seventeen. Easier backgrounds to handle are skies, rocks, and mostly anything that's far off in the distance.
Let's talk, assuming you're doing digital art, the perspective grid:
This chapter was the first one that took me weeks, and this setting right here is why. I can't show the process anymore, but if your background is any kind of interior, you NEED to turn on the perspective grid no later than the preliminary sketch stage and you need to get it right. If your room's proportions don't make sense, and they won't, because free handing that isn't happening, even the casual non-artist reader will notice something feels wrong.
The perspective grid takes a lot of time to get used to if you're like me but the tradeoff is you get a room with perfect proportions, like above, that you can then copy and paste into every other panel. It also makes it easy to quick add those great textures (in a room you're probably looking at bricks or floor tiles or wood paneling). That should be how you approach most interiors. Make a few great looking shots from different angles, and re-use them over and over. You can make the shots not feel so blatantly copy/pasted by zooming in/out, changing little knickknacks, changing the lighting-- but the only way you're getting that room is the perspective grid.
It's not cheating to copy/paste. It's not cheating to copy/paste. It's not cheating to copy/paste. No one is reading your comic to see you individually draw fifteen hundred bricks because "it's cheating not to" and you have never read a single comic in your life because you thought it was cool that they didn't copy/paste those bricks. Copy/paste religiously.
Also, don't put your furniture *on* the grid unless it's aligned with a wall. Your own furniture isn't aligned with the geometric proportions of your room, and unless you have a specific reason to make it so, Blorbo's isn't either.