A 2010 study shows that hands only CPR done by the layperson is just as effective as conventional CPR. This should encourage strangers to help someone in Cardiac Arrest.
Step 1: Recongnize That an Emergency Exist and Call 911
Your safety is paramount to your survival. If it is not safe for you to be there, call 911 and let the professionals respond. If it is safe for you to be there then check the patient for signs of unresponsiveness.
Step 2: Checking for Unresponsivenss
Shout at the patient and look for a response
Look for any signs of movement, bluish skin, chest rise with breathing
Step 3: Begining Chest Compressions
If the patient does not respond to you then you must begin Chest Compressions. Place the heel of one hand on the center of the patient's chest. Place the second hand on top of the first and begin pushing hard and fast. You will want to push at a rate of about 100 times per minute.
Think of the song "Staying Alive." Compress the chest to the rhythm of the beat. Continue doing compressions to help arrives.