First, and foremost writing for work or business communication is very different then writing for your English or history class. Business writing is the communication or exchange of information in a written format for the process of business activities.  It can take place between organizations, internally or between the customer and company. 

Writing for work is a basic component of your job - an internal memo, feasibility report, financial report, analytical report or a marketing report. 

• Writing at work focuses on problem solving.
• Work related writing targets multiple audiences with different perspectives.
• Writing at work may be read by unknown readers and/or readers outside of the company.
• Work related writing can be used indefinitely; moreover, parts of or whole documents can be used out of context.
• The format for work-produced documents varies greatly  - memos, letters, procedures, policies, and evaluations... 

Keep in mind it's a busy world, busy people do not have the time to read lengthy documents, most just scan for the key points.  Business/work related documents need to be clear and easy to read. Reports, memos and emails... should be inviting to read with bullet point and headings.

Before writing:

• Identify the purpose
• Identify the audience
• Identify the context
• Identify all of the facts and ideas
• Organize facts and ideas
• Identify the best medium for the message

Effective business writing follows the 10 c's:

• Complete – what does the reader need to know? What is the primary purpose of the message?
• Concise – keep to one page when possible. Do not use weak verbs, meaningless expressions or stock phrases.
• Clear – be aware of word connotations. Be sure to define the topic purpose, place and time.  
• Conversational – keep the tone of the message conversational. Write like talking face to face. However, do not use slang.  
• Correct – use correct spellings, format, punctuation and mechanics. Coherent – A coherent message flows together with all the parts fitting together and ideas connect. 
• Credible – use reliable, valid sources. The writer must be able to support their opinions. Beware of information bias, how the data was collected and how current is the data. 
• Concrete – give exact information using specific, meaningful words. Vague words are to be avoided. 
• Courteous – write in a positive tone, using positive language. Focus on what is or can be. 
• Considerate – design the document to be easy to read.
• Chunk information -  use bullet points, highlight important points. In memos, letters, and emails a paragraph is 6 to 9 lines not sentences.

Keep in mind business writing is:

• Logically written
• Well written
• Well reasoned
• Well ordered
• Done well