Basic first aid goes as far as diagnosis, for example as a former EMT if I saw a bone sticking out of someone's arm I'm only allowed to report a, "Possible broken arm." because I'm not considered a professional.
Another point is that as an EMT, while I am trained and have trained my nerves and reactions to high stress situations regarding physical injury and/or life threatening situations one thing I've always known was that I'm really only as good as my equipment.
You have your basics, scene safety (don't run over a downed wire for instance), body substance isolation or BSI (wear rubber gloves) and airway, breathing, circulation (A.B.C.'s). However if someone is bleeding out you would go for some form of gauze, say a t-shirt or a rag. If a man is having a heart attack on the other hand there's really only so much you can do after calling 911.
In short being prepared is always good but understand that mortality is a fact and there really is only so much you can do and you need to accept that the worst can happen.
All I'm offering are little techniques and piece of mind on a very small scale, do with them what you will.