Which is the best choice in a negotiation situation?

a. Contact the supplier to schedule a negotiation rather than waiting for the supplier to contact you, irrespective of whether or not you have a tight schedule 

b. Wait for the supplier to contact you to schedule a negotiation if you are not under pressure to conclude the deal soon 

c. Threaten the supplier than to appear weak 

d. Withhold your targets and get a 5% discount then disclose your targets and only get a 10% discount