i wanted to ask that how can you come up with a Social media marketing strategy for an organisation

Hello...
First of all you should make a company profile on the social sites like facebook,twitter etc.Make it attractive by using applications.Follow the people who are relevant to your comapny's product.Ask your client to follow you there.You can viral your genuine content their any update about your company,videos etc.You can also create events and contests to bring traffic.Ask you followers to send suggestion of frnds to you.Make followers and bring traffic...:)

Create articles or posts that valuable to people. Once they find that you don't just sell stuffs but also willing to communicate and help them, people will spread links to your site for free.

This is a very broad question ... it depends upon the goals of the marketing campaign. Social media can be used to increase brand awareness, increase conversions, etc. If you have an editorial or content-based site, you can have twitter/facebook like buttons like we do on DaniWeb. If your site has a login system, you can integrate Facebook Connect or Login with Facebook / Twitter / Google Plus / LinkedIn / etc. Create FB fan pages. Interact with customers on Twitter. There's a lot that can be done :)

Social Media Marketing is really very useful these days.......

Advanced Social media marketing strategy

Strategy 1: Multimedia Usage
Strategy 2: Integrate Offline and Online Advertising
Strategy 3: Message Adaptation
Strategy 4: Local Social Networks, Beyond Yelp
Strategy 5: Contests and Discounts

You have to be active on social site.. this is the main in promotion using social media sites.

Company Profile Page
Network Page
Fan Page
Social Advertisements
Comapny Groups

Its a very broad question and the below mentioned steps are likewise each of these steps has a lot more that you will have to work on.
1: Create Your Executive Overview Business Plan
2: Define Your Specific Social Media Goals
3: Find Your SMM Voice
4: Choosing Your Social Tools Appropriately
5: Plan & Execute Content & Delivery

1: Create Your Executive Overview Business Plan
2: Define Your Specific Social Media Goals
3: Find Your SMM Voice
4: Choosing Your Social Web Tools Appropriately
5: Plan & Execute Content & Delivery