Alright it's back to the basics. When focusing on Social Media it is very important to stay on track with the Marketing Mix (the 4 P's). Product, Price, Place and Promotion. In easier terms:
Who - Who will do each task to implement your social media plan (ex: you, intern...)
What - What will you need for your social media plan (ex: internet, fan page...)
Where - Where will you do your advertising & promotions (ex: twitter, facebook...)
When - When will this happen (ex: daily, monthly...)
Why - Why are you doing this? Set a clear goal for yourself.
How - How is this all getting accomplished?
Follow these questions and you will be on your way in no time. The more questions you ask yourself the better your plan will be.