The objective of an optimum DC bias is placing the Q-point on the load line where a maximum signal swing can be achieved at the output. This optimum Q-point is usually at the center of the AC load line.
DC bias of an amplifier sets the limits on the output signal swing. Hence, a proper bias design is of considerable importance in the overall design process.
It is a good idea to test your bias design by simulation in order to verify the accuracy of the design.