We all dream to make money when we sleep, guess what? There are some people out there that do exactly that.
With the right tools and research you can be one of them. The big mistake is to think that you don't have to do nothing and the money will come, no no no... I will give you a starting point and the rest it's up to you.
Where to start?
First you need to find the right affiliate market program. Amazon/Clickbank/Avangate/Aliexpress or others.
Second? Have a Website
There are plenty of possibility to promote a product with out a website but is much better if you have one if you want to buy traffic. You can buy direct traffic to your affiliate link only with bing but adwords and facebook they will block your link promotion. A product review page can be a easy solution to promote a product and also will be a great landing page.
How much money can i make?
There are no limits, at some point if you have a good ROI can you scaling it a lot. A friend of mine make between 1000-1700$ daily.
I recommend you to read Neil Patel is one of the best in domain and you can find a lot of information there.
If you are interested about the subject please follow. Regards AlexIM.