God has already offered deals to you. That is His prerogative. Turn to Him and you will receive eternal blessings. Ask Him and in return He will hear you and respond.
When we, however sincere, well-intentioned, and limited, try to make deals with God, what we are doing is making our relationship conditional, in the sense that our relationship becomes dependent on a certain result. God is privileged to establish that arrangement, but not us.
There are several fallacies I can think of in trying to make a deal with God.
First, is the above arrogance in placing yourself in the position of God. God makes deals with us, not the other way around.
Second, is that our desired result may not be what God desires and thinks best.
Again, we are trying to trump God in that we think we know what is best. It sure would be helpful if we always knew what is best. But it doesn’t always work that way.
Third is that we are dependent on any particular result in the first place. It is understandable and fair to desire a particular outcome from prayer. But don’t become dependent on one.