Hi there. It's hard to tell from the limited information. In general - if the conversion rate is measured by purchase vs visits I would say it sounds good. Perhaps you could share a URL to your landing page?
In order to maximize the conversion rates you can use A/B testing to find versions of your landing page that is more effective. See some of our case studies and examples here http://conversionlab.no/customer-success/
Generally speaking 30% conversion rates in the Internet Marketing Niche is considered doing well. I would certainly say you are doing well with the limited info.
Absolutely be sure to utilize split testing (A/B Testing) and there are ways to automate the process to alternate two landing pages without doing so manually.
Finally, I'd encourage you to track Clicks/ Opt ins as well as Opt ins/Sales. These are also two very important metrics when it comes to measuring the quality of your landing page. (If you are not collecting emails, def. do so asap to capitalize on the majority of sales that occur in the follow up series)