It's understandable to be very tired! What I like to do is put my work in stages.
I work on EVERYTHING for an episode slowly. I have someone storyboard and then I'll do 2 rough line art sketches then one final lineart. Believe it or not, sometimes the rough sketches are perfect enough for the line art.
Another one thing I look at is brushes. If you have a brush that looks into: trees, grass, skies, etc. then you have a hand up. Some people might view that as "cheating" but I think if you spend a few hours working on a brush that you can use to replicate what you've already drawn, than so be it. If you want to be spicy, you can even do brushes for body parts i.e.hands, eyes, body base, etc. I don't do the later because it doesn't feel right for me. However, I did make a braid brush since my MC has braids and it takes ages to individually draw braids.
Also, I use brushes in the rough line art and varying on how I feel, it's okay to redo something till you're happy with it. That's the beauty of brushes.
Colors are my weakness, so I can't really comment here. But doing flats, you can use the lasso tool and then paint bucket to get exactly where you want painted.
One thing to consider, it is okay to go slow. We all want to work fast but that comes with practice. Lots of practice. Just working a little bit at a time to sharpen your skills and learn new tricks will pay off in the end.
Lastly, make sure you love what you're creating. You notice when you are inspired by your story, you can work through it without as much ... pain.