To better your odds of choosing a movie worth watching, here are a few more ideas.
Find some good lists. There are some helpful lists out there that can guide you in finding worthwhile flicks, especially if you are young and/or have not seen many films. You may want to check the movies against a reviewer you follow, but here are a few to look at.
Experiment with a genre. Pick an interesting or unfamiliar genre. Film noir is getting some attention again (that's a good thing), and I would guess most of my readers are unfamiliar with it. Silent films, westerns, musicals etc. can all be fun places to dive into film. Determine the genre, find some books, websites, podcasts, lists/ratings and run to Blockbuster or log on to Netflix and get going. If you do the research this approach can be rewarding.
I will share some final thoughts on what to watch in part 3.