Payment mods in Islamic Market

In Islam , most preferable payment mod is in cash. It is a most easiest honourable way of payment. Islam educating the peoples that make the transaction preferably on cash.
If transaction is on credit, debtor should realise his responsibility. payment should be make on due date.If vendor is giving his Goods on credit, he should not demand the payment before the due date. On other hand buyer should realise his duty and he should pay his payment till due date.
credit transaction should be in black and white and by mutual understanding.