Copy writing is like no other writing that you'll encounter, but yet so vital to your success. This is the art of persuasion. Writing to convince the readers to take action. With out this ability your business will have little chance of success. You might be able to succeed with the shear numbers of visitors and play that numbers game. However the way I see it is you work very hard to get those visitors and taking full advantage of everyone who arrives is a must to keeping advertising cost down.
Knowing your product from every possible angle is really the only way you can differentiate between its features versus its benefits, and knowing how to turn features into a benefit. Knowing statistical facts and being able to write this in way that backs up its claims is important.
What really sets your product or service apart from everyone else? You never want to leave your prospects hanging there. The best way to know your products or services is by trying them yourself. This way, you can personally recommend them without the need for research or third party opinion.
Know your audience. Adapt your writing to the the typical reader in your chosen area of expertise. Know the lingo and terminology they use and connect on a deeper level. Being able to identify with with your readership tell your prospect you understand and are right with them and you get their needs. How can your product or service address these needs?
One of the best ways I know to really understand a market is to spend time researching your competitors. Go to 10 or 20 sites. Find out what they are offering up and bonuses and what is the main thrust of their sales message. You'll quickly understand the message they are trying to convey. Look at the questions that arise when you read their message. Write them down, these could be objections that you could answer in your copy.
Keep the information useful to those who read it. It helps maintain the attention of the prospect. Offer good tips and tricks or a few secrets that may seem obvious to you but may not be to your readers. And last but not least make sure it is written well. Spelling and the grammar is important. Make sure you use enough bullet point that bring the benefits to the forefront.
Answer as many objections as you can, so that your writing can bring a comfort level to your prospect. Online more so than anywhere else it is going to be about confidence in you and your product or service.