I just finished a 24-hour solo race. For the second year in a row, I followed the 24-hour Personal Best plan from http://lwcoaching.com/ Coach Lynda is wonderful, and her plans are tough, but do-able while working fulltime, and she gets results. Both years, I won the overall female division. She'll answer questions about your training by email, and she'll help you adapt the plan to your life.
For example, I have a business trip that falls in the wrong week of my plan - she helped me rearrange the plan to work around it.
I know, without a doubt, that I couldn't have won without her training behind me.
PW
For 3 days, I get to part of a thousand other journeys.