What we need:

initially:

name

trading name (if different)

address

phone, fax, email

a.b.n.

ongoing:cheque butts and deposit books

bank and credit card statements

misc dockets (e.g. petrol, parking, newsagents etc)

if you need debtors reconciliations, invoices you have issued to customers

if you need creditors' reconciliations, invoices you have paid to suppliers.