There are a lot of writing opportunities out there. This may also cause a bit of hesitation on the part of some writers. The types of writing can be broken down into three discrete categories: copywriting, journalistic writing and creative writing. Of course, there's quite a bit of overlap and some gray areas, but this is the simplest line that can be drawn to educate new freelance writers. So, where do you start? Well, that depends on two things: where you are right now and where you want to go.
Copywriting is (here) used as a catch-all term to describe the fact that you are writing copy. This copy may be ad/marketing copy, as in the more traditional sense of the word. But it also may be web copy, content for companies (business writing, tech writing) or content for publishers. Basically, it's writing pieces for businesses.
Many writers are at a sort of crossroads. Some have been laid off, while some are simply fed up and at the breaking point. If you're at a place where you need to put food on the table, you might want to begin with a copywriting career. This is because some kinds of copy work are easy to break into, offer quick turnaround, and can be high paying. Copywriting for the web can be a good target for those with little experience but a knack for writing, while those who have subject matter expertise can use that niche to get specialized jobs.
This major group covers writing for periodicals- whether they are trade magazines, consumer titles or newspapers. Although being published in print is a badge of honor, it's a little harder to get into. Freelancers with a background or education in writing may want to set their sights here. In addition, people with 9-5 experience in PR, marketing or similar venues seem to have an easier time reading and meeting these editors' needs.
This designation covers copy that is more, well, creative. Examples include greeting card verses, short stories written for contest money, and work-for-hire gigs such as wedding vows and funeral programs. Do you write for the love of writing? Do you write mostly as a hobby? Creative writing might be for you. The outlets for creative writing are slightly fewer and pay less, but are a good target for the "writer at heart."