The easiest way is to promote someone else's product and get a commission for the sales.
That way, you don't have to ship products and you don't have to do customer service.
We call this: Affiliate marketing.
So for instance, you join an affiliate program to promote an e-book: "how to stop your dog from barking".
The product costs $45, and you earn $30 per sale.
(This is realistic, a lot of programs like that exist).
Second, you will need to get a website..
Or wait, I said zero investment, right? ;) I am just kidding, you don't even need a website.
You can easily make a free page on sites like Blogger.
com (they are owned by Google by the way), Hubpages.
There are a lot of those sites that look great, and you can make your page there for free.
You call the site "dog-barking-solutions.
com" or something like that, and you provide a link to the sales page that you are promoting.
A very cool thing about those sites is: Google loves them.
So most of the time, within one day your new, free money making webpage will show up in Google search results! You can just check by Googling for "dog barking solutions".
But unfortunately it won't be on first page yet..
And to really get money from Google, you need to rank on the first page of search results, so people will actually click on your link and buy the product you are promoting.
So we have the page set up, and it shows up in Google (somewhere on page 9 or so).
Now how are we going to get it to that magical first page? Simple.
We rinse and repeat.
The most important factor for getting a good ranking in search results nowadays, is the number of links pointing to your webpage.
So we just make more free pages like the first one..
Exept this time, we don't link to the sales page that we are promoting..
We link to the "dog-barking-solutions.
com" page that we made! So every day you write an article in 30 minutes or an hour at most, make a new free webpage, and link to the first page you made.
Usually within a few weeks, but within two months at most (depending on the level of competition) you will have the result you were after: Money from Google with zero investment!