I read "Taking Charge of Your Fertility," by Toni Weschler which was an excellent source for helping me identify when I was truly fertile and target problems in the length of my luteal phase. With this information, I was empowered to eat a certain way during different times of my cycle to support the estrogenic forces in the follicular phase and the need for progesterone during the luteal phase of the cycle. (For example, I wasn't afraid of peanuts and soy products when estrogen was the dominant hormone, but after ovulation, I avoided estrogenic foods and ate foods that help remove phytoestrogens like broccoli, cauliflower, greens, and the other excellent foods for fertility below).
When my cycles were irregular/nonexistent, my doctor prescribed a regime with progesterone and clomid. This worked, but had awful side effects. If kickstarting my cycles ever became a problem again, I would turn to something like this FertiliCare program, using herbs strategically in an intended cycle. I used something like this prior to one pregnancy and successfully regulated my cycles in addition to feeling balanced and energized.