Everyone who has a computer, some spare time, an interest in the World and a good grasp of English can make a passive income from online writing. There are various online sites you can join and work for as a freelance writer, some of them charge you to join, others such as Helium are free of charge. My preference is Helium because it is a site which is friendly, professional and easy to navigate.
To make a passive income from online writing you need to be sure that you will be continuing with the project and not just doing it for a month or two. If you are not sure you are really interested in this or that you have the time then it may not be a good idea. Your passive income comes from having a lot of articles placed and it takes time to write that many. I would suggest that you look at your lifestyle and how much time you have, work out if you will be doing this full time, part time or very part time and work out some sort of rota or schedule to work by. Perhaps if you work from Monday to Friday in a normal job and have commitments during weekends you might decide that you set aside one evening a week or a part of Sunday to this. When you have decided this stick to it, do not get lazy and let other people and other things distract you so that today becomes tomorrow and you never end up doing any work. It actually makes more sense to promise yourself that you will write just one article a day for a year, gathering together 365 articles, than it does to say you will do half a dozen or so when you have time. To say when you have time means nothing as other things will always pop up and take over. If you anticipate that you will be very busy with new things such as a new job or moving or having a baby soon then either allow for this and tell yourself you will have less time then and it will take longer, or realise that you are too busy to take this on.
You need to be patient, if you expect to earn a lot of money straight away then you are not being realistic. Unless you are prepared to write a lot of articles and spend a lot of time on this your passive income will be just cents. You also need to be sure that your articles are of good quality and subjects people are interested in and need to learn about. Do not fall into the trap of writing stories and poems or talking about your boyfriend, it may be interesting to you or your friends but not necessarily to strangers. Stay away from articles that are topical with a short shelf life, such as current politics or religion, write about things that still matter and where the knowledge you share will still make sense in ten years time. While you are building up your residual income chance your arm at competitions and market place titles so that you can hopefully sell some articles outright too.