Starting with comm 1, most pilots prefer to have it set for the frequency currently in use. For example, if you are setting up for departure, comm 1 would be set on the ground frequency with the tower frequency in the standby box. Comm 2 should be set for the departure frequency. This way you can switch from frequency to frequency with one button push. If you know which frequency you are going to be passed on to after the initial departure frequency, you can set it in the standby box for comm 2.