Has the property been on the market long?
The buyer is trying to ascertain how eager you may be to sell.
Has anyone made you an offer?
Again the buyer is trying to identify your position and gain an advantage in price negotiations.
Why is the property for sale?
Valid reasons will not put the buyer off, but never say it's because of space.
Are you in a chain for buying another property?
The buyer wants to know how quickly you will be able to move should they decide to proceed with the purchase.
Has any major work been done on the property?
You may have receipts and guarantees that can be shown to prove that works have been undertaken. This can be a positive point.