Working as a contractor, you need to have a wide range of skills. Every company and every job situation presents new challenges and the more prepared you are to meet them, the more valuable you will be as a contractor.
Despite what many beginning technical writers seem to believe, there are no established formats or guidelines that have been adapted by all companies for technical writing. My experience is that every company has its own set of requirements for technical publications. Some are informal and some are set out in specifications hundreds of pages long, but all are different. Even in military technical publications, which all follow the same specifications, companies and even technical publications departments within the same company, will apply their own interpretations to the specifications.
You need to be familiar with a wide variety of software. While Word is the most common software used for writing, different companies use different versions. You may also find companies that want writers who have experience with FrameMaker, InDesign, Open Office Writer, or Word Perfect. They may also want you to be able to handle spreadsheets, databases, presentation software, and software to create online training modules.
It has come in handy for me to have some programming background and experience with relational databases. I got this building web sites as a hobby. Knowing how to work with HTML, XML, SQL, and other web scripting languages helps when you are writing about software.
In my current contract, I am not doing any actual technical writing. I was contracted by the agency as a technical writer, but the client (a mortgage company) calls me a “data consultant”. In the position, I convert documents templates from PowerBuilder database to custom XML templates for CaseAware (another database system). This involves writing queries for MySQL, translating the PowerBuilder logic to work in CaseAware, and testing the translated templates. I also find myself leading a team of writers who I need to mentor because they don’t have the experience with SQL, XML, and databases that I do.
Every bit of experience and education you can pick up will serve you sooner or later. In this job you cannot afford to specialize. You need to be an expert in every industry in which you may be hired. For that you need to constantly be learning and developing skills. Follow your curiosity wherever it may lead you and you just may end up with a job or jobs you will love.