Two words spring to mind here, integrity and airmanship
Slow n low is spot on.
Integrity comes from having the guts to put your hand up and admit that you made a mistake. Its only stays as a mistake if you fail to learn from it.
Airmanship starts back at the planning phase of the flight, ie study a map. Blue lines don't change but the red ones do, so go find some more info before you get airborne. "I didn't know it was active today" is a piss weak excuse for lack of planning.
In regards to letters from CASA etc, I couldn't care less what they do to the PIC of a VCA , if you srcew up, its up to them to decide what happens next. If its a really bad one and you've put people in danger, then maybe prosecution is fair and reasonable. If its minor infringement (error vs violation) then maybe a check flight is all that is warranted. I just have to sort out the crap fight at the time, what happens next is not my area.
But remember, that letter, the check ride or the phone call, may be all that it takes to prevent an accident down the track and make that person a better pilot.
Some advice to any newbies that find it hard to work out restricted areas.
If your not sure, ask centre. If your still not sure and your approaching an airfield, listen to the ATIS (should anyway). If that fails, make a broadcast on the CTAF freq, ATC will tell you if the place is active. Not all of us will bite your head off!