I use Letterboxd. Its pretty easy to get started, look up a bunch of movies you know you like, read some of the reviews, follow some people who seem like they know movies and would be into interesting stuff, and then see what comes your way.
Find someone who is more into movies than you are and talk to them regularly. :)
I got introduced to a bunch last year by making the acquaintance of a film grad student who ran a movie club that met via Discord every Saturday night to discuss a film of the week.
I think this could also probably be approximated by finding someone into film on social media, or watching entries accepted into well-regarded film festivals, or if you happen to have an active mom & pop video store in your area, talking with the clerks.