I'm usually deciding by first thing in order that allows me to:

1. description, tags, and whatever I see on the streaming / store / database website; works 90% of the time for stuff I won't like (1 of 10 I like something I didn't think I would) and 70% for stuff I will like (3 of 10 I don't like something I thought I would)
2. opinion of people I know - that can be a reviewer I've been watching for some time or a friend
3. comments to get some random details (some would consider them spoilers, my shite memory does not)
4. opinion of people I don't know - reviews, average rating
5. coin toss

I sometimes change my decision after seeing a random clip