Here are some questions to consider:
1) How many unique visitors come to your website?
2) How many visitors opt-in to your mailing list or order your products?
3) When you send emails, how many are opened and how many people actually click through to your website?
The reason these question are so important is because if you don't know these stats, you won't know what to improve. It could be different things; like your headlines, the content or navigation on your website.
You won't know until you start checking all your marketing offer.