Hi Andrew,
It would be in your best interest to get your self rescues dialed in before venturing out into these locations, As for each location Pinnaroo is probably your best bet until your pretty confident as it's a bit more forgiving than Mullaloo as it's pretty choppy there.
The guys that are about at those beaches are Darren and Rob you can find there details on there websites and give them a hoy they'd be more than happy to get you on your way kiting.
Pinnaroo Point: is Darren Marsh, found here:
actionsportswa.com.au/kiteboardingschool.com.au/index.php?option=com_content&task=view&id=100&Itemid=79Mullaloo Beach is Rob Gannon, found here:
www.kbp.net.au/Hope this helps
Enjoy & stay safe