Many studies and my own practical experience have indicated that triage is so important that it must be done by the most experienced medical personnel available. The triage RN must know not only anatomy and physiology, he/she also has to know appropriate treatments and the resources of the facility. Diagnosis should not be done at the triage point. Therefore DR's asn especially surgeons make for lousy triage.
Airway-Cspine, Breathing, and circulation are first primary assessments. If any of those are not intact and working everything else must stop. In the military those with compromises here are generally expectant. In the civilian world there is no such category. From there the head to toe assessment is done in1 to 2 minutes per patient. If there is no life threatening condition found in the first 60 seconds of assessment the pt is either delayed or minimal.
To do all of this in so short a period requires a lot of experience and a lot of practice. Triage is an ongoing event until the pt is released. Everyone makes mistakes. Hopefully they never result in death of a patient. But sometimes they do. When you make a mistake in triage you try to learn from it, and never repeat the error.
There are a number of classes designed to introduce the concepts and practice of triage. If you have to do this take every class you can. Good luck. Gary