A good diet with plenty of protein is the best thing you can do to encourage hair growth. Treating your hair well by not subjecting it to chemical or mechanical damage will help it to appear to grow faster, as healthy hair is less likely to break.
It takes a lot of time to grow out hair which has a lot of jump. I've been growing mine, with cuts for shape, and to remove split ends and knots, for about five years. Once the old growth was gone, I was a lot happier with it, but the jump is insane, and it's still just down past my shoulders when dry.
Baby Fine 3B, low porosity, normal density and elasticity
CGing since July 2008