Hi ethan89, welcome to WebmasterWorld!
There are many ways to make a living on the Internet. It is best you chose something which is within your own interests, because often it takes some years before a website really takes off, and in the period until that happens you have to put a lot of time and effort in it to make that happen.
If you know a lot about a certain subject, you could start a content site focused about that subject and monetize it with advertising like AdSense. If in real life you like trading and interaction with people, a webshop may be a better choice for you. And if you are good in algorithms and development, writing the next generation search engine might be the ultimate goal.
It all depends on your skills and interests. The main thing is that you chose a direction with which you feel comfortable to do a few years of work without much revenue.