Like everything else in life, it's gonna depend on what YOU are looking for, and what looks good to one person won't to another, hence LOTS of hits with the above keywords.
Gary
In the Hue/Saturation dialogue box, check Colorize.
The hue slider will jump to the hue (in degees from 0-359)of the foreground color. If that is neutral, it will go to 0 degrees which is red. There is no exact hue for sepia but it is in the vicinity of 30 degrees. That's the "good starting point" you are asking for. Set the slider to that value and tweak it in that general neighborhood and choose a value that seems right for you for the image you're working on.
When you check Colorize, the Saturation slider defaults to 25, which is NOT repeat NOT the saturation. I could tell you what it really is but that would be unnecessarily stupefying when all you need to do is experiment with it by moving it left or right in conjunction with the hue slider until you get a sepia tone that pleases you. Again the setting of 25 is a reasonably good starting point.
George