The keys to success are only 2: Good basic CPR and timely defibrillation when indicated.
Several studies have shown technicians can achieve better survival to discharge than paramedics because they concentrate on the 2 key skills stated above
Remember that no drug has ever been shown to improve survival to hospital. And unless performed very regularly, faults in intubation technique are likely to lead to an overall deleterious effect.
Effective compression demands achieving the recommended depth at the correct rate, with full release of pressure, and with sequences that have no pauses between them of more than 5 seconds.
Use of a defibrillation in automated mode must ensure that last compression to shock time is as short as the device will permit, and that compressions be resumed immediately afterwards.