Google has introduced a new page to let you manage your security and privacy settings across Google products in one place.
There is an incredible amount of information on the various pages hyperlinked, and it can be a bit overwhelming if you are not technically inclined. I suggest completing the Security Check-up and Privacy Check-up.
The security check-up checks your recovery information, connected devices, account permissions and gmail settings. The privacy check-up checks your Google + settings, phone numbers, Youtube settings, account history and Ads settings.