1. Get to know the users of the product.
Discover their needs, expectations, likes, and dislikes.
Learn what determines their purchasing decisions.
2. Become an actual (if only temporary) user of the product, or at least have it fully demonstrated to you.
Know the product intimately, to write about it powerfully--with the ring of authenticity.
3. See the product from the viewpoint of prospects/customers/users.
Discover the product's strong points and weak points, according to actual users.
Identify the product's most beneficial aspects. Produce new ways of verifying, emphasizing, and dramatizing them.
Anticipate, and devise honest responses to, valid objections against the product. (No product is perfect.)
Translate product features into user benefits. Avoid listing features divorced from their practical advantages to users.
Provide side-by-side comparison charts, both product selection assistance and competitive differentiation.
Product selection assistance means helping customers compare the features/options/prices of your various products, models, versions--so they can choose the product best suited to their needs and budgets.
Competitive differentiation means helping customers compare the features/prices of competitor products with your products--so they can see how your products are (hopefully) superior to your competitors' products.
4. Ask questions potential customers will ask about the product.
Favorable questions. Antagonistic questions. Smart questions. “Dumb” questions. Cynical questions. Unfair questions. Typical questions. Unusual questions. Easy questions. Difficult questions. Informed questions. Misguided questions. Polite questions. Harsh questions.
Prospects tend to earnestly ask, silently ponder, or scoffingly harbor, all types of questions about a product.
5. Obtain answers to these questions that will satisfy, and make sense to potential customers.
Devise answers that are intelligent, tactical, and true.
Respond triumphantly to skeptical prospects, without falsely portraying the product. Admit limitations, but emphasize desirable benefits.
6. Explain the product to prospects, in terms that are relevant and clear to them.
Prospects, customers, and users rarely use the same terminology as the corporate insiders, product designers, or marketing personnel.
Communicate in the language of typical users. Provide simple, direct explanations of complex aspects and difficult issues.
7. Present the sales material to potential customers to determine if it's relevant and clear.
Never assume potential customers will personally relate to and understand your sales promotion text.
Have representative prospects, the audience for your sales communications, read it.
Then ask specific questions about features and benefits to make sure they internalized the intended message.
See my post on Converting "Print Read" Text to "Web Scan" Text for more web writing tips.