Writing the text of articles and posting them on the internet takes some time (depending the subject and your experience), but once you set up a system it's easy to do this task (or job) as often as you can. The content of your articles is a great method to improve the traffic of a website, even when they are on other websites (with the condition of putting backlinks to your site in the text).
The search engines will take into consideration the content of your articles as the uniqueness and how long is the text. Do not copy and paste other people articles or you will damage your reputation from both points of view: human and search engines. The websites and blog that reproduce content from other sites are being penalized or even blocked (in extrem cases).
An article should be more that 300 words and it should be written around a single subject. Use targeted keywords focused on this subject, if it relates with something or someone you are passioned about it should be very easy to write your story. In the case you are promoting something the articles should related to a product or a service.
Probably one of the most important things is that the articles you are posting remain forever on the blog or the website (unless something strange or bad happens and the website goes missing), so you do the job once and you get the benefits for a long long time.
There are several tips how to improve writing articles (determine your topic, figure out your audience and research before you start to write) but it's up to you to determine if you are fit to do it or not. (Re)Search the market for the trends and what the competion offers and write your aticles in your own unique way. Some people are born writers, it's in their blood, and it's very easy for them to find the appopriate words to send a message. Others write 10 words in one minute and it's hard to understand what they want to say. But don't be worried: if you think you can write for living you should at least try it. Everyone starts the same and only the talent and experience makes the difference in time between bad and good writers.