I use the Kodak Sepia II as opposed to their regular sepia tone which is muddy and leaves to much warmth in the borders of the paper IMO. I would also emphasize the diluted bleach that others have mentioned. It can be pretty hot straight. I go 1:10 from the stock solution. It takes a little longer, but your tone will be more controllable. I also keep the bleach tray up out of the sink on the back of another tray turned upside down. I warm the bleach bath to a temp of about 72 degrees and raising it out of the wash water keeps it warm. I also will go back into the bleach and tone after thoroughly rinsing if I feel it needs more depth. This effectively helps you "build-up" your tone to the place you want. After this and another thorough wash, I will go with the selenium to my taste. As was said before, it will attach more to the darker values. Pushing either or both part of the process can lead to some pretty dramatic and evocative effects.