Check your local college or university for a technical writing certificate program. Look at the faculty of the program to confirm you are being taught by professionals in the field or working content writers who are familiar with the demands of the writing industry. Certificate programs can be beneficial for writers who are new to content writing or technical writing.
With the pace of social media and the frequency of blogging, not to mention that many of your content assets will be used across multiple campaigns and teams, a lightweight project management tool is critical. I recommend using a free software called Trello, which helps you organize your content, set deadlines, attach files, and collaborate with multiple teammates. Another great tool for keeping content projects organized from planning to publishing is Zerys -- a content marketing tool with a built-in marketplace of professional writers.
Quick turnarounds. When you write for an employer, on their timeline, you will need to be able to write fast and write well. This is especially true for writers just breaking into content writing. Often, your project will come with an expected words per hour, or article per hour, as well as strict deadlines. You will not have time to labor over every word or turn of phrase. Instead, you will need to produce content fast and at a constant rate.