Small businesses , including me are always looking for portable solutions when seeing clients and recently I have switched to Square to process credit cards when i see clients.
Square is a portable credit card reader which has a charge of 1.9% per transaction that can be used with iOS devices ( iPhones and iPads ) and Android smartphones and tablets.
The device costs only $19 to purchase and your transactions can be imported into many cloud based accounting packages including Xero ( my accounting package of choice ).
On your smartphone or tablet you will download the Register App for Square then plug the device in and charge clients.
The banking setup was extremely quick compared to some others and I had my Square account setup and functional within a couple of days.