Although freelance writing is a relatively cheap undertaking, needing, at the very least, access to a computer, freelancers will find that a few tools of the trade will ramp up their prose and help them to more efficiently write the copy that gets them paid.
The style book that a writer uses depends on several factors, including the discipline in which you write, the needs of your clients, and perhaps even personal tastes. Many style books offer both an online subscription service in addition to a printed manual.
Whether conducting interviews over the phone or in person, freelancers who write profiles or quote sources need a recording device. Prices vary widely, but a $30 no-frills recorder will be able to upload MP3s directly to your computer for transcription.
ReadPlease is software that reads your text directly back to you, hence helping with proofreading, especially in errors of omission. However, writers swear by their text editing program of choice. One that was recently recommended to me: ErrNet. Get more polished copy by using whatever works for you!
Again, your specific choice may be heavily dependent on the clients you serve. Certain industries will defer to certain dictionaries. In addition, some clients may require you to use specialized books. For example, an educational publisher that I worked for asked me to refer to a dictionary that assigned words to certain age levels- and I had to carefully mesh my vocab with the correct level.
Let's face it, writers get ideas on-the-go. In addition, sometimes dragging the laptop around just isn't realistic. Portable writing systems like the Alphasmart Neo may be just the answer to the "should I pack my laptop or not?" question. In addition, it's a good idea to have an even smaller system for capturing ideas and pieces of copy. Many writers report using small journals, cell phone memo features, or smart phone/PDAs to quickly net ideas to take back to the office.