It depends on whether you are after one set of preferences for your application, or one set per activity.
I’ve used code like this:
SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(getContext());
Editor editor = prefs.edit();
editor.putBoolean(PREF_NAME, false);
editor.commit();
and
SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(getContext());
if (prefs.getBoolean(PREF_NAME, true)) {
// etc
}