Hi
It depends on the demand and speed,
If you should be afraid of loosing the property, but you can try to ask your agent what the highest offer is, but you can only know if he is exlusive agent on this property or his company is exlusive, so if they are exlusive and are telling you the highest offer you know at what number you should come in, and you know how much time you have to negotiate on the deal ,
If you have no idea, you need to determine if you can risk the deal by comming in lower and you will save money or you will lose the deal,
But everything boils down to the same thing depending on the agent if he is exlusive and can give you a good feel,
If he is not exlusive give a offer and ask for a counter offer of the seller.
In some states it's illegal the agent should tell you at what numbers the other offers are, so you can tell him at my number are there any higher ones, or how is my offer comming in etc.