As usual, sources will be cited at the end.
I mentioned the jaw-thrust method in my First Aid notes a while ago. Here is another method to make sure a victim’s airway is clear if the victim is lying down: put one of your hands under the victim’s neck and lift it up a bit so the chin is pointing up. Put your other hand on the victim’s forehead and rotate/tilt their head with this hand so the victim’s mouth opens up. That should open the airway as well and then you can see if it’s being blocked by anything (like their tongue or something they were choking on before they fell unconscious).
If an adult victim has a pulse but isn’t breathing, give them one breath of air about every five seconds. (If there isn’t a pulse you should go right to CPR regardless of whether they’re breathing or not because if their heart isn’t working then they won’t be breathing soon anyway.) They make masks that cover the victim’s mouth and nose to make this easier and to prevent you from catching any illnesses, so if you have one then you should put it over the victim’s face. If the victim is, for example, a loved one who you know is healthy so you know no illnesses will pass between you if you give them the so-called “Kiss of Life” without the mask, then it’s up to you whether you want to wait for help to show up with one of those masks. Personally, I’d expect the person to be dead by then in most cases (the ones I’d end up in anyway) so I’d seriously consider not waiting for that to happen. Your circumstances might be different, so you might want to go on a case by case basis.
Signs/Symptoms: chest pain, gasping, shortness of breath, bluish skin lips and nails (sign of oxygen deprivation), and if they have heart disease they may have swollen ankles indicating this. Sometimes the victim will also have indigestion or be nauseous, and this may result in the victim vomiting.
You should put the victim in a comfortable position if possible. This will probably be with them sitting up and you may need multiple pillows for this.
Give them artificial respiration if they’re not breathing.
Have someone call for an ambulance. The ambulance should have oxygen to give to the victim (if their heart isn’t working properly, then this extra oxygen should help their blood cells from becoming too oxygen-deprived).
If the victim is on the ground, unconscious, and has no heartbeat, give them CPR. http://en.wikipedia.org/wiki/Cardiopulmonary_resuscitation#Methods Lace your fingers with one hand over the other as it shows in the picture and have your hands over the person’s heart as you hover over them. Push down around a hundred beats per minute (to the tune of the song “Another One Bites the Dust”). You want their ribcage to go in to make their heart beat, otherwise your pushing won’t reach their heart and the victim will have a smaller chance of surviving. (That again without the coat of sugar: they will most likely die if you don’t push down on their heart hard enough. As a side note: they can recover from a few broken ribs, but they cannot recover from death.)
“The American Medical Association Family Medical Guide” Medical Editor: Charles B. Clayman, MD (ISBN: 0-679-41290-5)
“Standard First Aid and Personal Safety” (“Prepared by the American Red Cross”) (ISBN: 0-385-15736-3)
And the final source today is Wikipedia (hence the CPR link).