[Nubtoubrem]

You mean play in the rain? Waterproof shell, rain pants if it's cold, wet gloves for when the grips inevitably get wet, extra towel, spare pair of socks in the car just in case.
Accept it's not likely to be a record score, swing a tad less aggressively if the tees are really slippery, try and pick the ball cleanly if fairways are soaked.

Up here, we just remind ourselves that it isn't snow. And all this doesn't apply if the rain's cold or a steady soaker, we just stay home then.
What you really want is a Brit or Scot to chime in. They have to cope with this a bundle.