Wilbinga would be a good place to start - you can get access from Dame Pattie Drive in Two Rocks.
Some sections are very popular so be careful when the track gets windy and there are lots of blind corners. Also, keep off the beach - it can be very treacherous (especially now) but there's plenty of hills/dunes/sand bowls to keep you entertained. Tracks go everywhere so you can get lost easily but you will always end up somewhere
Lancelin is great if you like sand dunes - lots of big open dunes - hard to get into trouble, but again - stay off the beach. The beach at Lancelin can be VERY nasty. And right now it's very bad.
Powerlines Track in Mundaring/Sawyers Valley is great - it's got everything from mild to wild.
Most people get on at Cole Rd and drive right through to West Talbot Road, but some people shorten the trip by getting on at Flynn Rd instead.
I've seen people get through the whole Powerlines track in 2wd but there are plenty of challenges along the way to test the most extreme 4wds as well.
There are chicken tracks at all the challenging parts.
Drive within your limits and don't take any water crossings for granted.
There are normal looking 'puddles' at the Powerlines Track that will swallow your Jeep whole.
If you want to head out with some other Jeepers, keep an eye on this (there are usually trips every month but we've been a bit slack lately
Western Australia - AUSJEEPOFFROAD.COM - AJOR