If you want to improve, it's vital that you know what's going in your website and landing pages. You'll need three kinds of tools for this: web analytics (discussed here), ad tracking software, and A/B split testing software.
The top names provide great analytics -- WebTrends, Omniture, Coremetrics, WebSideStory (HBX), and others. But frankly the cost of marketing and e-commerce-specific data is too much for small businesses.
For small businesses, I strongly recommend ClickTracks from CEO John Marshall. This program is available as either a hosted online service or software that analyzes your own logfiles. It also comes in Analyzer, Optimizer, and Pro versions. I recommend that you start with the Analyzer Hosted version for $49 per month. You can always upgrade to Pro of you need its features. With ClickTracks you can set up color-segment subgroups from among you site visitors (such as track all second-time visitors or all who subscribe to your newsletter) and see how different groups move through your site. With this knowledge you can begin to improve your site dramatically. ClickTracks also gives very strong support so you can track visitors by keywords from both natural and paid search. I use this myself and am delighted with it.
