The most important thing about affiliate marketing is to be producing top quality content and adding value to the Internet. There is already a plethora of junk websites online, you won't get far by adding to the pile.
It is usually not a good idea to build a website round a product either. Instead, you want to find a topic, niche, or hobby that you would love to write about over a long period of time, and build a website about that.
Then, when you add an affiliate product to sell to your audience, not only will it be more natural, but you will probably have a decent level of authority established and people will trust your recommendations more.
Furthermore, it will take time to research, test, re-write, and improve your website. If you are building it round a single product, or chasing the "hottest product" available, you will run out of enthusiasm pretty quickly. On the other hand, if you enjoy the topic you are working on, everything will be a lot more tolerable and will run more smoothly.
You can make money from virtually anything online. That doesn't mean that you can chase after the latest dream or promote anything under the sun though.
What it means is that if you are willing to do some research and produce some excellent content (either written by yourself or others), you can make money from almost any niche.
Never chase quick cash, it is ALWAYS better to build yourself up a solid business by helping others first, solving problems, providing solutions, answering questions and so on.
Once you have done the ground work, you will have earned their trust, and they will likely make a purchase based on your recommendations alone. That is where the true value in affiliate marketing lies.
This is 2013. People can smell scams and poor quality a mile off. Internet users are smarter than ever, and they want you to work that little bit harder to prove that you are telling the truth. All of this points to one thing.
Earn their trust by being trustworthy. Don't promote things that aren't any good, don't promote things that you wouldn't use yourself, and don't promote things that are fraudulent. Simple.
It might seem like a lot of work for very little payoff. Indeed, in the initial weeks or months you might not see a penny despite spending hours building up your business.
That is the point though, once you have built that business tall, built it on strong foundations, and with solid materials, that business is going to earn you stable income for some time. Then you can go and find something else to write about, another awesome affiliate product to promote on it, and rinse and repeat.
Simply put, to make a living with affiliate marketing, you need to treat it like a long haul business that you are building. People seem to have unrealistic expectations for the Internet, when in truth, the Internet needs quality just as much, if not more, than elsewhere.