I went from mid brown to fully grey and then back to mid brown over a 1 year period and would suggest you:
1. Go slow - it is a massive transition, not just for you but also family and friends. Take it slowly and give everyone (including you) time to adjust. This was my major mistake.
2. Be strong and confident in the direction you are going - sadly not everyone will be supportive and it can be exhausting having to justify your decision.
3. Find support for the journey - There are some great websites/forums that provide encouragement and brilliant advice. I found them invaluable.
Good luck, going grey is an empowering and liberating thing to do!