The book that first got me interested in toning was "Creative Elements" by Eddie Ephraums. It's very detailed and there are formulas for mixing your own toners, etc. Be sure to try thiocarbamide toning, as you can control the tones by using different proportions of the stock solutions (it's similar to sepia, without the odor). Chemicals can be obtained through Photographer's Formulary or Artcraft Chemicals.
If you happen to be using Ilford MGIV-RC paper, try lightly bleaching the print, then sepia toning with Kodak's mix, followed by selenium toning (1:6). It gives a beautiful (and archival) tone that isn't as brown as straight sepia.