You can make your own hours, writing as much or as little as you want. Depending on how far you want to take it, of course. Some may want to do some random pieces, while others choose to immerse themselves into freelancing. The path you take is up to you, but a few tips can be helpful. If you are going to write occasionally, you have to go to the right place.
Many web pages offer one-time submissions, while others offer more permanent positions.
The best way to see what is out there is to start searching. Expect to spend some time learning about the field. The Internet is a great place to start by using search engines. These are imperative for you to be aware of. If you are not, you're spending your time writing and you won't be able to attempt to match up to the company's standards.