This might seem like a simple question but what do your customers really want?
The overriding principal in most human interaction is 'what's in it for me'. Applying that to business - What will this product do for me?
The typs of questions that circulate through someone's mind when they are deciding to purchase something are:
Will it make me more money?
Will it save me time?
Will it make me more beautiful?
Will it make me feel better?
Will it make me healthier?
Will it make my life better?
To get the most out of any marketing campaign you need to appeal to these points of self interest.
After all, when it comes to actually making buying decisions, people generally don't buy what they need, it's what they want.