If you already are a retailer with a shop then you have the basics in place. For those who wish to become resellers they need to straighten out the basics.

• Register a business entity as a one person company, a limited liability partnership or a private limited company and keep ready the registration certificate.
• Open a bank account in the company name and keep ready passbook and cheque book.
• Obtain GST registration certificate. This is indispensable. You will have to file monthly returns but you can assign this task to a CA or someone who handles tax work.
• Address proof for place of business address and identity proof
• Phone number
• Email ID

Scan and keep electronic formats ready. You will need to furnish these when you register at Amazon. If you have confusions then you can always hire an expert for Amazon seller registration. Apart from Amazon registration you also receive assistance with GST certificate.