Most of the times, you just set up writing at once after understanding the product in your individual way. It is something similar to you are taking part in a running contest; while everyone stands on a straight line and the instant the whistle blows off, you just start running without knowing about anything except for to finish the race as soon as possible. Possibly this particular approach is appropriate for running competition, however not for technical writing. Here, you require to do so many things prior to you start writing regarding a particular piece of software or equipment. Read further to be familiar with what you should do.
User guide or documentation is nothing than just conveying essential information regarding a particular piece of software to the layman (end user) who is going to make use of it to achieve his/her own purpose/ mission. Technical writers have the ability to present highly intricate terminology-driven software functionality in an easy layman terms. In addition this is as well what end users want. End user is just like a layman. They are not interested in multifaceted terminology or in the software's ultra-advance functionality. What they really look forward is to perform his/her part of work by means of the piece of software as speedily as possible and efficiently.
Before you start writing a user guide, being a Technical Writer, you have to know your end audience. You have to revise them including their operational habits. You need to recognize how they have been doing the similar job; so far, physically as well as where does this novel piece of software will go in their working lives. Then, you have to think regarding how you elucidate the software functionality to these end users in the simplest and understandable terms.