You've received good advice so far. Let me just add a few more pointers.

You need to make as clean a contact as possible.
- Setup with the ball in the middle (or a little back) of your stance.
- Have an very early wrist cock. This should promote a steeper blow on the downswing.

The rough will snag your clubhead and affect the clubhead speed and clubface angle.
- Hold the club tighter than normal. In a scale of 1-10 with 4 being the normal, hold it with about a 9 grip pressure.
- aim a little right of the target.

What club to use
- I still get the same distance from whatever club I use. The reduced carry is made up by extra bounce/roll due to lack of backspin.
- I can normally use up to a 5 iron from the rough.
- I bought a 9 wood (Cleveland) early this year to replace my 3 iron. I also discovered that it was so easy to hit it from thick rough. It was lofted enough to get the ball up quickly and it still gave me about 200 yards. I highly recommend this club.