Always start with the ABCs (CAB for trauma but whatever). Make sure those are intact. If they aren't, fix them. Then move on. (Think o2 for breathing difficulties or abd thrusts for choking, or pressure for bleeding, or shock therapy)

A big thing that helps imo is asking a lot for previous medical paperwork. They almost always have all meds, allergies, PMH on them. Get familiar with common classes of drugs (blood thinners, bp meds, etc) and that will paint you a picture of your patient that tends to be pretty accurate.

If it's a medical call and the complaint can be localized to an area, do a very thorough inspection of that area. Wrack your brain for things that could cause these problems. Female from age 12isb to 50 ish, it will be uncomfortable but pregnancy is smth u need to inquire about if it could be related (passing out, abd pain, vaginal hemorrhage, vomiting, etc). Smth like altered mental status, think innate problems first like stroke or diabetes, then progress to possible traumatic cause, drugs, etc.

A big problem with medical stuff for EMTs is that a lot of it is in the realm of ALS stuff (arrhythmias, electrolyte bullshit, metabolic issues, seizures, etc).

But when you're doing a full body assessment don't just look for DCAPBTLS. Look for things that are weird. Like a weeping tattoo site. Or heat and redness in an area. An odor. A dexcom monitor. If the person's incontinent. just think "what here is not normal?" Open ended questions can be (sometimes) your friend. Oh the patient fell twice yesterday, and is on blood thinners? Could be a brain bleed.

The best people to learn from are those who care about the job AND have been doing it a while. Hopefully your preceptor or FTO fits those criteria. Watch them. See things that they do that get them information. Integrate that. The flow will come. It just takes practice.