The best way to get started with this process is to look at what truly makes sense and is legitimate ways to make money. You will also want to look at different methods that you might be able to try first to see if they work for you.
One of the simplest ways to make money online is by selling products and services that are already available online. For example, you could create your own website and sell other people's items for a commission. Or you could place an ad in a newsletter or on a forum about a service you offer.
People who can offer several different reasons for why they need to sell something will likely get more business than someone who offers just one reason. This can be a great way to start up a business, and many people will provide it as a job to supplement their other income streams. It may be worth trying out something like this for a couple of months to see if it is something you are comfortable with.