According to a USA Today\/Gallup Poll released this week, 70 percent of Facebook members are "somewhat" or "very concerned" about their privacy. Take into account the site's past privacy flubs and it's easy to see why: a privacy breach, prevalent "scammy" apps and constant change keep Facebook users on their toes.The last reason, in particular, makes it difficult for Facebook users to keep tabs on the always-evolving privacy environment--settings are split into two main categories: account settings (which include some privacy settings) and the main privacy settings pageHunting for specific privacy settings can be tedious, so we've done the work for you. Here's a list of five of the most important Facebook privacy settings, where to find them and how to change them.1. Facebook Check-Ins and PrivacyWhen Facebook announced its location-based check-in service, "Places," in August 2010, it was quickly met with concerns about its people tagging feature.With this feature enabled, your Facebook friends can tag you and "check you in" to a place. You receive a notification when you're tagged, and an update is posted on your wall telling your friends where you are and who you're with. You can remove the tagat any time.To disable the feature, visit Account > Privacy Settings > Customize Settings. Scroll to the middle section--"things others share"--and click "Edit settings" next to "Friends can check me in to Places."Another important Facebook privacy setting to review if you use Places is whether or not you want to be included in a "People Here Now" list once you check in to a location.By default, your name and Facebook profile picture appear in the list, which is visible to anyone--friend or not--who checks in to the same location. To disable this setting, visit Account > Privacy Settings > Customize Settings, and then uncheck the box at the bottom of the first section that reads, "Include me in 'People Here Now' after I check in."2. Revoking Facebook's "Instant Personalization""Instant Personalization" debuted in April 2010 to plenty of criticism, and for good reason: The feature is confusing and Facebook's online explanation does not make it clear how participating sites use your information.If you visit one of the sites that supports Instant personalization--Bing, TripAdvisor, Rotten Tomatoes, Pandora, Yelp and others--and you've enabled the feature, you can see which of your friends have "liked" certain movies or news stories and browse reviews they posted. Additionally, Instant Personalization uses information you made public on your profile to recommend movies or songs, for example.The first time you visit a site that supports Facebook Instant Personalization, a notification message appears that lets you turn off the feature, if you want.Otherwise, to enable or disable Instant Personalization, you should visit your Facebook Privacy Settings page, then choose "Edit your settings" under "Apps and Websites" at the bottom. Scroll to the bottom, click "Edit Settings" next to "Instant personalization" and uncheck the box on the next page.3. Facebook's Social Ads and PrivacyYou might occasionally notice ads in the margins of your Facebook profile and elsewhere on the site. These "social ads" pair an advertisement with actions your friends have taken, such as liking a Page.A few important things to understand about social ads: Advertisers can't see information about you or your friends, nor do they have access to your private information. Facebook doesn't sell your information to advertisers and says it won't in the future.If you participate in social ads, your friends might see information about you that relates to the ads they're seeing. This may be a line that says you have "liked" a certain page, or they could include your profile photo with your name next to the ad. Here's how to opt-out of social ads displaying your "likes."Once again, visit your Account Settings and click the "Facebook Ads" tab. From the drop-down menu, choose either "No one" or "Only my friends," depending on your preference.Note: A disclaimer on this settings page explains that while Facebook does not give third-party applications or ad networks the right to use your name or picture in ads, "If this is allowed in the future, this setting will govern the usage of your information." So if you don't ever want your picture being used as an advertisement, ensure this setting is up to date.4. Information Accessible Through Your FriendsWith all the time spent trying to shore up the privacy and security of your own Facebook profile, there's an important setting you need to remember to update to help ensure that your friends don't expose information about you.When your Facebook friends use games and applications, those appls can request information about other friends--i.e. you--even if you don' t use the app. This information can include your bio, photos, political views and places you check-in to.To prevent this, visit Account > Privacy Settings > Apps and Websites. Click "Edit Settings" next to "Info accessible through your friends" and uncheck any necessary boxes.Note that while you can prevent your friends' applications from accessing most of your information, your name, profile picture, gender, networks and user ID (along with any other information you've set to "Everyone") can be accessed by Facebook apps. The only way to ensure all your information is private is by turning off "platform applications and websites."This privacy setting is located on the same page: Under "Apps you use" choose "Turn off all platform apps," and Facebook shows you a list of apps and websites you'll be disconnected from.For more information on Facebook privacy:Kristin Burnham covers Consumer Technology, SaaS, Social Networking and Web 2.0 for CIO.com. Follow Kristin on Twitter @kmburnham. Follow everything from CIO.com on Twitter @CIOonline. Email Kristin at firstname.lastname@example.org.