First start with one and then start the other. Don't two things at the same time. What I mean is for example you started affiliate marketing you need to stick to it and succeed once you are successful you go for another source of income.
That's when you will have a multiple stream of incomes.
Yes, affiliate marketing is a good place to start. Then, as you see what you enjoy the most, you can take different routes. If you are artistic, you might design digital products or sell print-on-demand design products (t-shirts & gear with your designs), or possibly design graphics, logos or fonts. If you are technical you might want to design websites or develop smart apps. You can even resell domain registrations, web hosting, servers & security certificates. You can setup a web directory and sell advertising, but then you have Google as a competitor and they will very definitely be evil.
Believe it or not, I am doing all the above. Plus now I am starting the long process of setting up a brick & mortar web host/server site.
But there are many different ways to start. Your expertise is what is important, so pick something you enjoy doing, something you have a passion for. If it is writing, write an e-novel or how-to do-it-yourself manual, or whatever you are best at.
The main thing is content. You really have to come-up with a lot of it, so if you are into photography or drawing, start there.
There are good free website builders that create really nice, simple and optimized websites, like Mobirise (though you have to pay to take advantage of advanced features like premium themes, PayPal shopping cart, HTML/CSS coding). But they have lots of competition, too. Almost every web host has a free website builder and they have gotten easier to use, as well (though often they can be a little harder to figure out, they usually have great support staff). Probably, the best site builder and content management systems is MODx or SimpleCMS, but WordPress is usually a free install; a simple click-to-install web app (script), no matter the host, that uses a pretty easy design/management system, although you do have to keep it up-to-date (meaning if you don't keep the software up-to-date, which is easy to do, it will likely be hacked because it is so targeted by hackers due to security holes always being patched).
For promotion use friends to help spread the word and social networks to post new updates, news and changes. Announce yourself on Press Release platforms whenever you have newsworthy content, updates, new products, etc.
Oh, I forgot to mention... if you are good at figuring out what emerging trends are, or great at marketing and branding, you might consider domaining. But that said, I would establish an online presence, first.
Domaining is the process of researching, speculating on, investing in, developing and optimizing domain names.
For instance, I have a domain that is ranked in Bing and Google as the #1 website listing for the term "Ion Pulse Drive" (probably), right under the YouTube videos. Now, this is an older technology, but it is just starting to emerge and has already been used in spacecraft.
I say 'probably' ranked #1, because these search engines also go off my browsing history, and I'm not going to do an anonymous study about it. But because it is ranked so high, it may well become a valuable domain to someone who decides to break-through with this technology. Then again, it may take another 60 years to develop it where everyone wants to use it, but it may well power autonomous flight in the future, or it could be the title to a sci-fi novel one day.
BUT, that is a very tricky profession. I have sold one domain for a couple grand that I registered for $9. But I also have a bunch of domain names, and that $9 registration fee renews every year for as long as you hold onto each domain name. So, that one requires a decent investment and a lot of work. But some people really do well at it, understanding what names are worthy and then buying them and flipping them for more, without ever even setting up a website for the name, just knowing who should have what name.
Yes, your right Affiliate marketing is good, but that need sale, if your not getting sale then you will not get income, AS per my own suggestion that You can also try Freelancer, Upwork, Fiverr for your multiple income sources that will be direct method for