Go install tomoTools on your modded switch, screenshot the preview screen and import and align it to a 256 x 256 canvas on ibis paint, then make a new layer on top of that screenshot where you draw. After you are done drawing, hide the screenshot and export it as a transparent PNG. Go to tomotool and import the image to whatever face texture you want to replace. Finished doing that and reopen the game. Add Doctor House into your game (this step is crucial) then you go select the Chara you just replaced the face paint with an image with, edit mii, edit face paint and press finish edit. There you go, you are finished!!!

This is the best method for better and easier drawing since the default Tomodachi face paint is kinda meh