Fly the maneuvers as you have been taught.
If you make a mistake...correct it as best possible.....and move on....don't focus upon the mistake in the past instead focus upon what you are doing.
Be professional....answer questions as best you know how.
Give the examiner a nice helicopter ride...keep him informed of what you are doing and planning to do as you go along.
Call out your Checks....take your time but do not dally around.
RELAX!
I learned to fly helicopters in the US Military....and some check rides determined if you proceeded in training to be an Aviator or wether you went Infantry....and that during wartime puts a lot of pressure on you to perform.
In your situation the worst that happens is you have to retake the Check Ride....so the only pressure you are under is what you place upon yourself.....so RELAX.
Last bit of advice.....don't wear brown shoes with a Blue Suit.