There is no BEST way. There is only one way that is your way. Everyone has a different path to a million, each and everyone has their own strengths that they can cash out as a million.
Speaking of which, only for eCommerce you wouldn't need that huge credibility to start with. The profit margins would be around 10% to 30% normally. So if you have some ad budget and you know how to whip up an eCommerce funnel – with some persistence and patience you can do a million in sales and take home about $50k to $200k in profit.
The second best way to make some quick cash is to be a consultant. And that doesn't need any investment at all. Almost whatever you make would be pure profits, but you need to build credibility and need to have the credentials to be trusted as a consultant.
Many of the online millionaires are sales rich but profit poor. i.e. they sold a million worth of goods and probably made $50k or maybe even $300k. (There are exceptions of course, very few may have made higher profits than what I'm talking about here)
The common false perception these boasting online millionaires give is that it was too easy, they never talk about the failures they've had in the past, the chargebacks, the refunds they had from the $1 million they made, how much did they pay out to affiliates, and how much did their ads cost, how much was the affiliate manager's commission. etc.
All they speak about is the million dollar sales they made.
You better come up with your own financial freedom number, which includes the amount required for you to pay-off your outstanding debt and live comfortably (with your current living conditions) for the next 5-10 years.
Then make it an aim to hit that in the next 90 days…
Then slowly move towards a million or $10 million.
President Obama just received a $350k paycheck every year for being the President of The United States… Not a million.
I'm not discouraging you in any way to not dream about the million. You should. But plan your path. And your path is unique, you can never be another person and make that kind of money. Be yourself.