Social media is still relatively new in terms of marketing research and the formulation of workable models. Anecdotal evidence suggests marketing departments find it difficult to establish how social media fits into the company brand.
Most small companies just don't get Twitter! Full Stop.
The model suggested below, hopefully can be utilised to formulate a strategy for both small and large organizations.

Over View of the Model
1. Objectives
The first step, as with any strategy is to formulate coherent objectives and goals. The overall marketing objectives should be set in the marketing plan. It's important not to move off in tangents, social media should wok to achieve the overall marketing objectives of the organization.
For example an overall marketing objective could be to; improve brand or service awareness; Kenya Airways (@KenyaAirways), increase online customer interaction; Adobe (@Adobe) or extend customer services online; Virgin Media(@Virginmedia).
2. Segment & Target
With clear objectives set, segmenting and targeting the market using social and geographic demographic data is required. Who will the organization follow? Existing customers should be the first target, followed by potential customers in the target market. Possible targets could be based on: age, location, product usage and current brand awareness.
The organization should know its target market already. Twitter will not change the target group.
3. Twitter Brand
If the organization has an existing brand how will its values be communicated using Twitter? What language will be used and by whom? Who in the organization will 'tweet'? And, how often?
The style of the tweets, including the formality is key to the over all strategy. If the brand is 'professional', this should be reflected when tweeting. To preserve the professional image, the brand may follow a 'Tweet Only' interaction strategy. Example; CNN (@cnnbrk).
If the objective is to raise brand awareness and contribute to online customer service, interaction is essential: Virgin Media (@virginmedia) Easy Jet(@easyJetCare) American Airlines (@AAirwaves)
Brand Disruption - The threats to the brand or organization must be measured and potential issues addressed. Abusive Tweets, trolls, disgruntled employees, hackers and competitors could disrupt the brand and cause potential damage.
4. Message
Message: What's it all about? What is the organization going to say? Will the messages be tweet related from web site feeds? New York Times (@nytimes), Wall Mart Special (@WalmartSpecials) or will the Tweets be more formal and interactive? T Mobile Press Office (@TMobileOfficial) or adhoc based on customer needs American Airlines (@AAirwaves)
5. Integration
Two main aspects that could affect the 'message'.
Will Twitter be used as 'stand alone' or integrated into other social media? Facebook or Utube. And, is offline marketing going to contribute to 'push' customers onto the organizations social media platform?
The key is a create a clear message, and generate synergy of any other social media or off-line marketing. The strategy could be to use Twitter as a stand alone client facing tool, with little push from other marketing efforts Adobe (@Adobe) or Twitter is the face of the organization; Bill Gates foundation (@BillGates), Twit Pic (@TwitPic)
6. Communication
The final part in the implementation of the plan is to start 'communicating'. The only way to see if Twitter will work for any organization is to start.
Brand disruption plays an important part in the actual 'doing' and should be monitored. A small business, charity or a global brand could be badly damaged by employees deliberately sending gratuitous 'tweets'.
7. Measure
Hourly, daily, weekly. Feedback is paramount. Collect as much data as possible, concentrate on goal achievement. The outcomes are what matters, simply measure what happened against what the organization 'wanted to happen'
Be prepared to change and adapt.