Keep those responsible for implementation, those who will be affected, and those outside the school who have influence over the outcome aware of the plan and willing to lend support. Talk is only talk. Now you need to act. Public Relations is very important here - let your supporters know what's happening. Provide professional development for staff.
Effective training is essential.
The best training will provide staff with several opportunities to examine the issues, work together, and monitor and evaluate the progress. Once you influence change, for example a more comprehensive curriculum, then you need to insure that the teachers are prepared to deliver these lessons. Sexuality is not a topic that's easy to discuss. Teachers need to be given the skills to be effective and comfortable teaching. Evaluate and revise the plan.