It would be foolish to claim that there is only one way to take a portrait, but there are some accepted norms and basic camera settings that you should understand if portraiture is to become your area of photographic interest. Remember though, as you walk down your creative path, that a portrait is more than a headshot, more than a beautiful photo of your subject; it is an opportunity to get to know someone, to have a visual conversation with a person, and to use your photographic skills to pass that understanding of the person on to the viewer.
Cameras are a fluid piece of gear when it comes to portraiture—Nan Goldin used a beat-up 35mm Nikon in her early work and Richard Avedon used an 8×10″ Deardorff camera, among others. For some photographers, high resolution is critical to a good portrait, while others prefer a dreamy softness. In general, full-frame mirrorless, DSLR, or medium format cameras are the choices of experienced portraitists. But do not limit your creativity because of the camera you don’t have; find ways to interact with your subject and get to the moment where they are showing you their true self and be ready to capture it. Andy Warhol did it with a Polaroid Big Shot camera.