I like this slight sepia tone.
What is allowed ? First of all: Everything, I need to like my pictures, I dont need to please someones specific requirements for film vs. digital. Do what you want !
But here I want to reduce to the minimum touchup, like you would do in the darkroom.
The slides or negatives I scan, aftwards check the gradation or contrast. Then do some toning. In the lab I was using Kodak Selenium to produce a similiar effect.