Online marketing you can do through e-bay or amazon.com. Now go to the sites, open an account. You should have a credit card for online marketing. Open a Paypal account for security. Go to paypal.com and open an account with your credit card. To prevent fraud don't use your email account name or your name as paypal account name. Use something like 123lady or likewise so that it would be difficult to access your paypal account for others. What some sites do, they ask you to open your account there. Many a times what happens you put your email account name and password as your paypal account. Fraudulent sites may use ur email account and password to rob you. Beware.
Now opne and account in ebay or amazon. What you like to sell? Suppose I stay in Mathura. I say I'll send Mathura's famouse peda or sweets to US-based NRI's. I put a price tag on it with a premium for mine. I used to sell tinned Rosogollas or famous bengali sweets to non-resident bengalis. I used to charge Rs. 300 as my commission over the sweet's price in local market and courier charges. Canned sweets stay fresh for over a month and courier takes only 2-3 days to deliver.
Once my business got running, I used to make Rs. 20,000 per month. It would support my college expenses. The work load is nothing. I used to check my mails for orders, call the sweet shop owner in my locality. He would deliver the can of rosogollas or sweets within half-an-hour. I would call the courier guy - he would come and pick up the packed can with address on it in about an hour. With 10 minutes of time spent, I get a commission of Rs. 300 or 7 USD.
Payment was in advance, already deposited in my paypal account. I am still supplying different varieties of sweets through internet to non-resident Indians. You can try it too!