For Australia, you are extremely confined as to what you can do with a PPL to earn money. Skywriting as people have mentioned, will probably mean you lose your license here. What you can do according to CAR 2.7 (Civil Aviation Regulation) is essentially;
- Crop Dusting on a person's property using their aircraft (only on their property)
(You would also require an Agricultural Rating for this)
- Transporting the owner of the aircraft
Now, here's where you can work within the rules. According to the definition of the CAR, you can logically fly charter flights as private if you are transporting the owner of the aircraft. What if the aircraft is owned by a company? Logically, anyone who works for that company is considered an owner, or goods reasonable similar to property of the owner.
Now, take everything I've said here, take with a grain of salt as I am not a CASA lawyer (Thank god), and as a disclaimer, nothing that I have said here can be taken as an exact interpretation of the law or anything reasonably similar.
But, have a read of that CAR, and you will possibly find avenues to follow, or just bite the bullet, go to a VET Fee Help approved school and do your CPL?