The last waypoint should be 20-50 miles from the destination airport. Anything in this range should work. When flying in Europe you can usually achieve this by leaving the STAR out of the flight plan. In the U.S. and Canada the STARs are much longer and you will probably need to include some of the STAR waypoints or your last waypoint will be too far out. In rare cases (remote areas) you may need to use your flight planner to create a user waypoint to use as your last waypoint.
If you want vectors after the last waypoint, before connecting PF3 be sure the STARs box at the bottom of the SIDs/STARs page is not checked. If the box is checked you will not get vectors after the last waypoint, but will be cleared to complete the approach to the assigned runway on your own.