Step 1: Go to the Android Market and update your Spotify app.
Step 2: Launch the Spotify for Android app, then in the lower right-hand corner, tap on “More,” then “Settings.”
Step 3: Check the box next to “Private Session.”
Step 4: When you go back to your playlists, you’ll see the “Private Session” indicator at the top.
That’s it. Now you can listen to Spotify without advertising your playlists to your Facebook friends. Keep in mind that after 6 hours of idle time, Private Session will automatically disable itself.