Of course, if you just want to make your Google account more secure, you can employ plenty of tweaks to make it difficult for anyone to hack your account and sneak a peek at your personal data. If you also want to ensure that you're sharing as little identifying information as possible while browsing the Web, simple changes such as opting out of personalized ads or clearing your Web search history can help to keep your private data off the grid.
To bolster your online anonymity even more, you'll have to take drastic measures and start deleting your Google service accounts. While it is possible to shut down parts of your Google account selectively while keeping others intact (cancel your Google+ account while maintaining your Google Reader list, for example), you should probably delete your Google account entirely if you're concerned about data privacy. Before you do that, consider taking advantage of Google's Data Liberation Front to download all of your documents, photos, and other personal data from Google's servers. PCWorld security editor Nick Mediati walks you through the process of liberating your data and pulling the plug on your Google account in his comprehensive Google Privacy Checklist.