First of all, let me clarify a couple of things.
By watch, I mean sitting or lying down to intently, purposefully watch a movie or TV show, ideally with the lights off or very low vs viewing with the TV on and your doing other activities like being on the computer (like I am now, TV on as background), doing chores, exercising, etc.
99.9% of what I watch is either Japanese, Chinese (Mandarin and Cantonese) or Korean. None of which I understand, so I definitely need subtitles.
I’m OCD and once I discover someone or something, I’m compulsively driven to find more, ideally to completion of everything related.
One of the main ways I decide what to watch is admittedly entirely superficial. If I see a particularly attractive or entertaining actress (I’m a guy) on a TV show, series or movie, I’ll look up the movie or series she’s promoting, download (through various means) and watch it. I have dozens of complete series and all the movies featuring actresses that I’ve only seen once that I have to get around watching.
On a more cerebral level, there are actresses who are so outstanding in their performance, I seek out more of their work. One of the reasons I love Asian cinema is that usually both actresses and actors don’t confine themselves to a single genre. They may appear in a dramatic series for several months, then star in a completely comedic movie immediately after.
Then there are directors. Like actresses and actors, many Asian directors don’t limit themselves to a single genre. Once I see a movie I like or even don’t like, I’ll seek out the director’s other works as they may be completely different than what I first saw.