Stay with her initial offer price but throw in things like: make the offer unconditional (if she can) in writing with an attached cheque for the deposit, put in a vendor favourable settlement date in the Contract of Sale document, make the deposit higher (25% instead of just 10%) and offer a Section 27, make her offer only open for say 24 hours with no negotiation and tell the agent is is a best and final offer and make the offer strictly confidential to the agent and the vendor. Be prepared to walk away.
If she really wanted to play games take the asking price and divide by 11 and multiply by 10 and you might get the vendors lowest price.
