I know that everyone is different, but let me share what is working for me.
I have always taken a multi-vitamin. However, for the last 5 months, I have added Biotin- 4000 mcgs-- to my daily intake. I decided to add one vitamin at a time, so that I could determine what is effective and what is not. I am now experiencing an extra 1/2 inch per month of growth, for a total of a little over an inch per month
. As soon as I can, I will post pictures of the length of my hair as I track my progress. So, needless to say, I suggest Biotin (I take Puritan's Pride, but there are many great brands, as some of the members may have already suggested). I hope this helps!