There are more than a thousand ways to optimize your website to maximize conversion rates. The following excerpt from Andrew B. King's Website Optimization explains one of the top 10 factors to maximize conversion rates.
Your offer is a call to action. You are asking your visitors to act: to purchase, sign up, or opt in. Well-drafted calls to action motivate users to move further into the sales process.  For example, this:
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 Eisenberg, B. et al. 2006. Call to Action: Secret Formulas to Improve Online Results (Nashville, TN: Thomas Nelson), 144.
Learn more about this topic from Website Optimization.
Is your site easy to find, simple to navigate, and enticing enough to convert prospects into buyers? Website Optimization shows you how. It reveals a comprehensive set of techniques to improve your site's performance by boosting search engine visibility for more traffic, increasing conversion rates to maximize leads and profits, revving up site speed to retain users, and measuring your site's effectiveness (before and after these changes) with best-practice metrics and tools.