Invoice printing guidelines ?

Hi,

My Question is regarding 'Invoice Printing' Guidelines. So far i'm generating invoices on blank A4 paper without any prior invoice no or name printed on it. Now i wanna follow the guidelines. 

I want to know can i use normal A4 paper as my invoicing stationary with inovice no & my company name already printed on it & continue generating invoices on desktop printer or is it mandatory to use the invoice rolls wthat has two carbon copies which are compatible with only dot matrix printers.

Kindly Please help.

Regards