Having been involved in running internet businesses for over 10 years now this is a question I always get asked and one that always causes me much time for reflection.
In all honesty I have to say that my answer to this has seldom changed from when I was first asked this question way back in 1998.
Before I answer, let me list some of the basic internet business models around today:

1. Sellingproducts on eBay
2. Runninga membership website
3. AffiliateMarketing - selling someone else's products for a commission or bounty
4. Sellingcommodity products via a retail website - products you and others canpurchase from relevant suppliers and wholesalers e.
   g.
   televisions, floortiles, holidays, flights etc.
   
5. Sellingyour own developed products via a retail website e.
   g.
   software, prints, DVDsetc.
   
6. Runninga niche user-generated content website such as a forum or messageboard andmonetising the traffic.
   
7. Buyingand selling domain names.
   
8. Runninga niche content website where you add the content and you monetise thetraffic and/or build an email list to sell/recommend products and servicesto.
   
9. Runninga niche website where you acquire leads and you sell them to relevantcompanies.
   
10. Developingand running a blog and monetising the traffic and/or build an email listto sell or recommend products and services to.
    

I'll stop at 10 models but there are a large number of them out there.
So, what's my answer to the question? Well, back in 1998 I actually started out by accidentally buying and selling a particular domain name that I bought for $70 and sold for several thousand dollars.
If you know what you're doing this can still be a highly lucrative business but NOT for beginners.
My actual answer is selling products on eBay.
Let me explain why.
Firstly, you don't need much technical knowledge to sell anything on eBay.
All you need to do is spend an hour or so figuring out how to set up a listing.
Second, I can guarantee that you will be able to find something to sell around your home.
I often do a clear put of my garage and find numerous items to list and I make a decent amount of money from selling them too.
It's also dirt cheap to set up a sales listing on eBay and find thousands of eager buyers all across the world ready and waiting to buy them.
Selling simple household items on eBay also helps you learn about the basics of eCommerce, writing compelling sales listings, taking payments and shipping your items to customers.
I regard this as a series of fundamental lessons if you want to run a successful internet business.
It's a risk-free way of starting an internet business too.
I know so many people who have started out this way and made millions from their internet businesses.
It's also true to say that many of them moved into using other internet business models too but all tell me that eBay gave them that first start and valuable lessons in the fundamentals of eCommerce.
So, check eBay out today because there's a world of opportunity waiting out there.