I think to be useful you would be better off taking a CPR class though - knowing how to initially manage cardiac arrest, respiratory arrest, and airway obstruction is 1000x more useful for the layperson than knowing advanced treatments that you can't actually perform.
^ This. Don't take this as an attempt to squash your altruistic intentions. Rather, maybe to shed some light on how to focus them in the right direction.
If you do not want to read anything below this line, here is the answer to your question:
1). Buy this book-
http://shop.aha.channing-bete.com/onlinestore/storeitem.html?iid=179730
2). Search on this website for a class near you and take the basic CPR and a basic first aid class to learn
how to use this book:
https://www.enjoycpr.com/classes
The things that will save a life are what Cawolf mentioned above: CPR, how to clear an airway, how to administer an Epi pen, how to control hemorrhage, and how to identify when all the contents of a first aid kit in the world will not stymie the problem.
Brief disclaimer: when I refer to "outcomes" I am talking about
mortality (live or die) not
morbidity (quality of life) as the subject. My favorite medications in the world to administer to a patient are antiemetics (stop vomiting/prevent nausea) and analgesics (pain medicine) because they provide relief from suffering.
I've got a bit of cognitive dissonance regarding this topic, since I work in EMS and I believe in the improvement of patient outcomes. This means I promote bystander CPR at every opportunity. Not to get too deep into the weeds, but here is an attempt to explain what Cawolf mentioned.
The "gold standard" according to the NFPA for an ALS emergency in an urban area staffed by a predominately career department is to have ALS on scene within 8 minutes of dispatch on 90% of calls. Vomit. What does that actually mean? Nine out of ten calls that are determined to need an advanced life support unit, based upon emergency medical dispatching criteria, should have an ALS provider on scene within 8 minutes. Not only is this poorly defined as to when the clock "starts," but it also does not apply to a majority of the United States, since it refers to urban, career fire/EMS departments. I joke that I am classically trained since I started as a volunteer firefighter.
http://www.nvfc.org/hot-topics/key-fire-service-facts
The science behind this standard was from a 1985 publication regarding factors that increased a patient's chances of survival from v-fib/v-tach cardiac arrest. Granted, my opinion is that this NFPA standard was largely (I would say overwhelmingly) propagated by special interest groups attempting to either justify additional staffing or to establish clear metrics for the service that they provide. But does ALS improve survival outcomes? For the most part, I don't believe it does. I just made my former union brothers and sisters recoil in disgust over this comment, but for EMS I believe this is accurate. Firefighting is different, and I believe it is important to make this distinction. Anyways, a common complaint I have heard is either "what took you so long" or "I called for an ambulance, why did a fire truck show up?" There is a paucity of data for these standards, but there is some recent research on this stating that it may not really matter for
most calls. Moreover, what the limited evidence appears to demonstrate is that BLS is king. ALS does not improve outcomes and in some cases, like trauma, it actually makes it worse.
http://www.lmvas.org/pdf/isenberg.pdf
Ultimately, this is not an attempt to bash EMS, but rather to stress the importance of
basic life support. Survival outcomes have been correlated with three of the four links in AHA's Chain of Survival:
1)Early Access-recognize the signs of a patient needing emergency care. Maybe you can get this from a book that you seek. Realistically, a basic first aid class and basic CPR satisfy this link.
2)Early CPR- can't get this from a book.
3)Early Defibrillation- see above.
4)Early Advanced Care- research demonstrates that "early" means a response time of less than 4 minutes by a paramedic.
http://www.ncbi.nlm.nih.gov/pubmed/15995089.
Take a first aid class and a CPR class. Your family, friends, neighbors, or some stranger on the street may thank you one day for it.
