The craft of writing

The two most engaging powers of an author are, to make new things familiar and familiar things new - Samuel Johnson; and that essentially sums up the craft of writing.
The most important aspect of writing is the purpose. Why would you write something? What do you want to convey to your reader. It is desirable that you state clearly the purpose of your writing on the topic. This tells the reader clearly, what he should expect out of reading the prose. Thus defining the purpose should be your first step.
In technical writing too, we have various objectives to achieve, when we write various documents. For instance a maintenance guide/user manual for technicians, will have a different purpose when compared with a sales proposal, or material for advertisement. The style of these documents will vary widely. A maintenance guide will have an objective and informative style, whereas a sales document will have a highly subjective and persuasive style of writing. The type of audience and the purpose of the message should be kept in mind, while deciding on the style of writing.
To keep with the purpose, and to convey correctly, what you intend to convey, you need a very good language, grammar and vocabulary. You should be familiar with the various styles of writing and tones of language. Technology keeps changing and so you should be a person who is willing to learn new technologies quickly. Self learning and a penchant to update new information in your chosen field of work will take you very far.
Even accomplished writers admit that their first draft had lots of redundancies and gaps. It is improved by reviews and tight editing. To be a good writer you should have the patience to make innumerable revisions to your draft. You should be willing to take critisms and learn from them. Writing is a craft that is polished through practice.
Another quality that is necessary to be a good writer is to be a good reader. In Stephen King’s words “If you don't have the time to read, you don't have the time or the tools to write”. Even if it is documenting technology, the amazing vocabulary, and syntactic variations that you gain through wide reading will improve your writing. You would be able to discern why you like reading certain authors, and magazines, even though the hard facts maybe the same in all magazines/material on a topic. You can adopt that style for communicating with your audience. Thus writing is a craft that has to be practiced, to bring out its finesse.