The Right Questions
If you're able to get the attention of a potential customer, it's important to make sure their attention isn't wasted. You have to make the most of that initial conversation (whether that dialogue takes place over the web, through an ad or on a call).
It's the natural instinct of a consumer to be a skeptic. They start asking questions about your product right away -- questions aimed at determining if what you have is something they need/want and if it will provide a payoff in the form of some benefit (either emotionally or rationally). They may ask the person next to them if they've heard of your brand, they may go to google to research what people are saying, and ever increasingly they're starting to hit up twitter to see what others are saying.
The good news is that you have an opportunity to answer the questions before someone else answers it for you. You can overcome their objections and give them a reason to believe in what you're selling. Answering these questions is easy. The hard part is figuring out which questions to answer. Answering the wrong questions will result in being ignored. You'll end up talking past your customers, instead of talking to them.
The easiest way to figure out what the right questions are, is put yourself in the place of the customer. Write a persona that provides a sketch of your potential customers. Reading the persona should make them feel like real people. It should identify their needs, their anxieties and their wants as it relates to your product.
After you put yourself in your customers shoes, then you need to look at your product in an objective manner. Figure out what might prevent a customer from buying what you're selling. Is it a comparison with another product, is it an issue with the price you're charging (the price doesn't equate to the value they perceive), or is it a concern that it just won't work (does this camera work with my specific computer)? List out every possible question that you would have if you were in their shoes and try to answer those questions in as straightforward a manner as possible. Overcoming these objections and answering these questions is a core goal of marketing communications.
But, there is almost always one question that trumps all the others. Manufacturers of household goods try to find a single problem they can definitively solve, they refer to it as the "Ick Factor." Why should you buy a disposable sponge on a plastic stick for cleaning the toilet? Because touching a toilet with a sponge in your hands is gross and your toilet brush is disgusting.
Attention + Answers = Success.