I found it quite straight forward, I did it on a classroom course at LBA back in 2007. Few things have changed since then but I always recommend to people about screwing up. If you screw up a transmission just simply end it with “Disregard” or use “Correction” terms and then retransmit again.
I was given a mayday on the frequency where I had to relay the information onto test ATC so make sure you have your pen and paper available.