Olly: If you are looking at domestic transactions within Australia, the quickest, cheapest method of receiving money is direct transfer into your nominated bank account - everyone here is using net banking in some form or another.
Paypal is probably OK for international transactions but If I recall correctly (haven't used it for years), they charge a fairly significant commission?
Mobile Eftpos (Electronic funds transfer point of sale) machines are now available for quite a small rental cost. Many tradesmen and on site service providers are now using them. One example here (there are dozens of choices)
http://www.getmeeftpos.com.au/?gclid=CISWz8n2prICFZBUpgodOkEACQ You can complete CNP (Card Not Present) transactions with these if the client provides their credit card details.
Face to face, credit card is big but for mine, in a small business, even today 'cash is king'.
A few people are still using cheques - in the business I manage, which is part of a very large conglomorant, we still write a surprising number of cheques, maybe 50 per month but we also use direct EFT (Electronic Funds Transfer) quite a lot.
For personal business, I very rarely write a cheque these days - all EFT or Bpay.
Bpay
http://www.bpay.com.au/ is another option. It may be expensive for a small number of transactions - the business I manage doesn't use it for either debtors or creditors but I use it from a client perspective for my personal creditors such as electricity and telephone suppliers, kids school fees and so forth.
Australia Post Bpay
http://postbillpay.com.au/ is yet another option - frankly, I don't know much about is as I have never had cause to use it.