scarf joints? They never heard of them. In a closet on one of first houses I did in that place is probably only coped joint in entire development. I forgot to miter one end of shoe, didn't realize it till I got to that end.
Away back when, closets were where new guys and apprentices worked, you're liable to find some real fine meticulously done joinery in there. Along with some real thin shavings.
Measure twice, cut once.
Look at the nail, not the hammer. Watch the fence, not the blade.
If you hook your thumb over your belt you won't hit it with the hammer or leave it layin on the saw table.