The bad news is that many people fail to address these foundational issues, often without realising they've done so until it's too late.
The good news is that they aren't that difficult to address. It's just a matter of knowing what you need to do. Let's take a look at them.
Objectives
If you don't know what your piece is intended to achieve, there is little chance of it achieving it. That's a general business cliché restated and sounds painfully obvious. Nonetheless, the creation of marketing pieces and other business documents with no clearly defined purpose is so common as to be almost the norm.
Ask yourself why you are writing this copy at all. What do you want it to achieve?
Typical initial answers to such questions run along the lines of "We need a brochure to give out at next month's exhibition" and "We need a leaflet to send to people who show interest in our telemarketing campaign".
Such answers are fine as a start point, but you need something more specific. Maybe your piece should result directly in increased sales. Perhaps it should drive more traffic to your website. You need to identify what the actual purpose of your piece is.