Colouring your hair a darker colour (brown) with extenuate the re-growth it might be worth taking your shade a little lighter or even considering a scattering of high-lights. If you really want to stay dark then just colour your roots combing gently into the mid-lengths this should protect your hair from excessive dryness from over-processing and colour build-up. ...More >
If you are colouring your hair at home, although I would advise to have your hair coloured professionally, if you prefer to do it yourself look for hair colourant that contains no ammonia (ammonia free). Ensure you use a deep conditioning treatment at least once a week, this doesnít have to be an ordeal simply cleanse your hair with a colour protection shampoo, rinse and apply a small amount of mask to the mid-lengths and ends - leave for 5 mins max and rinse then apply a small amount of your regular conditioner - this seals in the moisture from the mask - rinse and dry as normal. Your hair should be glossy and renewed in no time.
Hope that has helped.