The community advice is that portrait photography is too broad to master through one checklist, and that hands-on practice is the fastest way to improve.

A good starting exercise is to practice lighting on a mannequin head or other patient stand-in subject. That lets you repeatedly test light placement, direction, and intensity while clearly seeing how shadows change across a face. It’s especially useful for learning portrait lighting and flash without tiring a real model.

Beyond that, combine practice with structured study:

• read portrait-photography resources and existing Q&A on portrait topics
• break the subject into smaller skills such as composition, posing, lighting, working with subjects, and post-processing
• ask or study each of those as separate topics rather than trying to learn everything at once
• if possible, take a live class or join local lighting/strobist meetups for feedback and demonstrations

In short: practice often, start with simple lighting experiments, and learn portraits one sub-skill at a time.