It is definitely safe to take only the fenugreek; however, you might get better results if you add in a few others. For example, Saw Palmetto, Fennel, or Borage or Flaxseed Oil.
I am fairly new at this myself, so I am no expert, but from what I have read, those are quite popular here.
It is perfectly safe to take only fenugreek. Just know that it might take a bit longer if you are taking only one herb. On the other hand, you may be one of those lucky ladies who only needs one herb to grow.
-------------------------
Those who cannot remember the past will spend a lot of time looking for their cars in mall parking lots. -- Jay Trachman
Read through this forum (newbies page, general reference page) and learn about NBE. I would advise you that if you are doing it, do it right, to prevent being disappointed and cause you do want best chances to suceed right? Personally I advise at least 3 herbs for growth, maybe 4 or 5 + an oil. Like for example: fenugreek, fennel, wild yam and nettle and borage oil. The choice of course depends on your hormonal im/balance. Then you have herbs for other problems, like cayenne for slow circulation, ginseng for stress etc... Good luck!