Here my read on the two holes.
#15 - as a couple of players have mentioned, if in a good position - I would go for it with your second shot. You need to give your shot backspin to get it up in the air. I seem to end up just short on the front left side. From there with practice you should up and down without to much trouble. If you have a tail win you should be able to put the ball on the green, try and land it in the front fringe and release onto the green.
#18. To get your second shot to stop on the green, try to land it on the up slope on the front right hand side of the green over the right hand trap (on the narrow entrance to the green). It will then release up to the middle of the green around maybe 10 yards away. Or - go straight for the pin and land it over the trap in the rough or fringe - thats a bit more difficult, you need real precision either way.