Having a passive income is a great idea and suits every person with any lifestyle or situation. It is particularly suitable for those who like to think ahead and make plans for years to come. By investing time in building up a passive income you will have a regular income coming in and you could put this money to good use either to pay for luxuries or essentials.
How much you earn will depend on how skilled you are and how much time you invest into the project. One of the wonders of building up a passive income is that it continually grows and there is no need for it to ever stop growing. If you have a lot of time and you are willing to invest it in building up a passive income you could be working towards having a fair bit of money coming in after a few years' time.
The best way to generate a passive income is to find an online writing site that you feel comfortable with, such as Helium. Some of the sites charge you to join and others charge you a monthly fee to be a member, so these are probably not worth your while if you will only be writing now and then. If you will be writing for your passive income every day as a serious thing then maybe it is worth the expense of belonging to a writing site. However, Helium does not charge a cent and it is a very good site.
Once you have joined your site decide if you wish to work full-time or part-time depending on how busy you are, your other commitments and interests and how much this means to you. The sooner you get a lot of articles under your belt the sooner you will see some money trickling into your account on a daily basis and as you add to your articles these income will steadily increase. It is a good idea to aim to write a certain number of articles per day or per week and then stick to it without allowing other things to side track you and maybe work it out based on how much you realistically wish to be earning in the future. If you wish to earn a high income you need to write a lot of articles.
Make sure the articles you write are of interest to others, you would be amazed at how many people write poems and stories about their cat and want everyone to read them and the truth is that not many people are particularly interested. If you write articles about current affairs your article will have a very limited lifespan as it will be of no interest or make no sense later on, so write about things that are interesting to lots of people and will still be interesting and make sense in ten year's time.
It makes more sense to write one article which is bringing you in a good income for many years than spending a lot more time on writing a dozen articles that brings in the same or less. If you wish to write reviews of products you can place your reviews on various different sites so that you are earning from that same article many times. All in all, having a passive income is a great idea if you do not mind some planning, some work and using some common sense.