The old proverb goes like this:

"He who hesitates is lost!"

What that means to you as a marketer is a prospect who dithers and delays is a sale that more than likely doesn't happen. Which is bad all around - for the prospect, who could vitally use the service / product you offer... and for you, because you failed to get the prospect to take action immediately in your copywriting.

Here's a kick butt "Call to Action" Copy Structure I recommend you consider in your copywirting:

1. Summarize the offer.
Make clear in a nutshell what it is your selling.

2. Show Value - Price - Discount - Net Cost.
Each one leads on to the other, piling up value as it rolls along.

3. Include the Guarantee.
Make sure it's clear, powerful, and creatively labeled.

4. Provide Payment Options.
People are used to payment plans. Breaking it down into 3-pay or even more can definitely increase sales.

5. Add Bonuses.
Wrap up with a clear listing of everything else you're tossing in to sweeten the pot.

When a prospect hesitates, nobody wins. It's important that your copy drive urgency by reinforcing the need to act now!