I'm still adding to this list of time savers for comics, but like these are some of the main ones I like to put in my face.
1. You don't need all them layers lady
2. Preselect your colors and STICK TO THEM gal
3. 3 passes on line art is 1 to many, stop and move on
4. If your stuck on a scene that's not coming together just stop. Work on something else and come back fresh.
5. Could this be better? Sure. Is it so bad you need to redo the whole thing? No. Are you sure? No, but I'mma move on anyway.
6. Script it out before you draw it out.