Everyone has/develops their own ideas on what is right or what works. For people, we usually stick with whatever our parents used or what worked for us but asking a friend never hurts!
Maracyn 1 is good for gram-positive bacterial infections (symptoms: clamped fins, swollen eyes, heavy or rapid breathing, patchy coloration, change in swimming behavior or corner hiding) and Maracyn II is for gram-negative bacterial infections (recommended for the treatment of Popeye, gill disease, fin rot and tail rot, etc). Maracyn and Maracyn II both come with charts that giude you through the symptoms to tell you which one to use. I've had mixed success with both of them.
Another common one is Tetracycline but I haven't personally used it. Its good for both internal and external bacterial infections. Both epsom salt and aquarium salt can be used but for different things I think. I've only used Aquarium salt and it seems to work decent but don't use it for more than 10 days at a time. Its cheap and worthwhile to have. IAL drops would also be a great idea. I just ordered IAL leaves off Aquabid.com but don't know how long they can be stored. If you don't already, get a complete liquid test kit so you can act quickly if needed.