Google makes it pretty easy to keep most of the fields in your Google+ profile private. Here's how to do it.
First log in to Google+ and visit your Profile About page.
Click Edit Profile.
Click a field in your profile to edit its visibility. To the left of each field in your profile you'll see an icon that identifies the visibility of that field. Here, I'm selecting the Bragging Rights field to adjust who can view it.
Now click the dropdown to adjust the privacy setting.
Several options are available. Choose among Anyone on the web, Extended circles, Your circles, Only you, or Custom. I'm going to make mine viewable to anyone on the Web who visits my profile.
Hit Save to apply your changes.
Notice the icon has now changed to a globe. That signals global visibility--that field is now visible to anyone on the Web.
Check each of your Profile fields and select who can view them. Click Done editing.
Getting to know all of the privacy settings available in Google+ lets you have a more secure profile.