Good question, research is very important in the copywriting process. I'd start by brainstorming before you start writing your copy.
1. Find your target audience
Who will be buying your product?
2. You need to understand the product you're writing about - benefits, features, purpose etc.
It's important not to have a skewed view of your product, you need to find the features of the product that the user base cares most about. Simply telling them what it does is not enough. Find the true appeal of your product.
3. Research keywords
This one goes without saying, effective keyword research will help bring visitors to your site.
For the main structure of the copy, I usually start with a description of the product or company. Then I can start analyzing the information. When writing about features I using write a point, explain that point and then evaluate it. I usually end with an overall evaluation of the product. I've used the example of selling a product here but I'm sure these points can be extrapolated and transferred.