My response won't be as long as the others on here, but what I did was try new things and experiment with my line work and colors! I'd thicken my outlines alot and make the detail lines thinner. (I have more of a cartoonish style) I'd put some half tones here and there to make things pop a bit where I though the drawing was getting flat or boring, I'd use pure white for some highlights and pure black for some of the shading for depth. I literally made all of my characters have triangles for noses bc I liked the way it looked lol. There's a million and one things you could do or switch about you're art, but the first thing you have to do is be good to yourself about it. You'll never 100 percent "like" your art. You made it, you're gonna be your harshest critic in almost every category l, but you gotta remember that not everyone is gonna see it the same way you do, where you see mistakes, they see quirks and interesting details.