There are several different ways you can approach making an offer. You can offer a lower amount and then negotiate a price with the seller. Unfortunately, if another buyer makes a higher offer during these negotiations you may lose the property if the offer is accepted. Or alternatively you can choose to make your best offer upfront and hope that the offer is accepted as you have no room to negotiate from here.
An offer should be formally made in writing by the sellers agent and prepared in the format of either a contract of sale or an offer of purchase. Sometimes the buyer will be required to provide a holding deposit when their agent makes a formal offer for them. If the offer is turned down then the holding deposit is returned. When the buyers agent makes the offer to purchase a date should be given when the refusal or acceptance of the offer is confirmed to save prolonging this process.