I’ve got a few:
1: I stopped doing a final “smooth” ink layer because it was an exercise in futility. My hands are simply too shaky and I was never satisfied with the results. Instead, now I started doing my final “sketch” layer in black (my prior sketch layers are always in bright contrasting colours: first layer might be red, second might be blue, third might be green, but the final now will be black). This gives my art a rougher, warmer, less rigid look and I really like it.
2: Before colouring the image I copy that final black sketch layer, then paste it as a new layer so that I have two identical layers. Then I make the original the active layer and rough colour it with the flood tool. Because the black lines are so rough and sketch like this leaves a lot of tiny empty spaces, which I then go back and fill by colouring the edges just like you would with a coloured pencil. Since this is all done below the top most ink layer it is not important to “stay in the lines”, since that top most layer will hide any straying.
3: in keeping with that same tip, before I start colouring I will create another new layer and flood it with a violently bright, gaudy colour. This layer will be placed below the colour layer and serves only to highlight the small areas that I may have missed colouring (if I can see any of the bright layer through the coloured one it means I missed a spot). I use a bright colour instead of plain white because Daecon has white hair and feathers and therefore a white background would only serve to hide missed spots (for example if I used white I might not notice that I forgot to colour his teeth or eyebrows). Once rough colouring is finished and I’m satisfied that I haven’t missed anything I discard the bright layer.
4: If there are to be several scenes in the same room I will copy & paste the background. I might rotate it, stretch or shrink it, skew it, change the lighting, or do whatever is needed to make the angles work in a different scene, but this is a LOT quicker than drawing the whole background again!
5: This is probably the exact opposite of saving time and I’m sure there are better ways around it, but when I’m doing final colouring I will first flood-erase the rough colouring in part that I want to colour (say, a face), then hit ctrl+c, then ctrl+z to undo the erase. This puts a copy of the layer in the computer’s memory with a hole in it shaped like that component. I then do my shading/lighting/textures/whatever, with absolutely zero regard for staying in the lines. Once I’m satisfied with the colouring I hit ctrl+v and paste that layer with the hole in it on top. This new layer covers everything that I didn’t want to have shaded, and the “hole” leaves the shading on the component that I wanted to shade intact. I then merge this layer with the one below, and then repeat the process with another part (say, the hair). Then the torso. Then the arms. Then the legs. Then the feet, and so on.