What do I use for my SDV Portraits?
I use aseprite, I actually bought it a long time ago on humble bundle but use it on Steam, or you can get it on the official website.
Aseprite
I put each face expression into a new frame instead of making folders with each expression like how I did it in Paint Tool Sai. Since you can easily export all of the frames easily into the proper size as the SDV portraits.
Just click Export Sprite Sheet
In Layout just copy what I did, you won't be able to Export just yet, you'll have to go into Output.
Now you'll be able to export.
I like to personally use the mirror tool but sometimes it's better not to use it, I used to be really afraid not to use it but now I'll turn it off whenever I don't want to mirror, I probably wouldn't use it at all if I chose to put them in an angle instead of being head on like I chose to do\~