Resources for learning to write about movies?

I feel like I should preface this by saying that I have no ambitions to be a professional film reviewer.

What I want is to learn to improve the way I think about, talk about, and especially write about movies, all for the sake of self-improvement and getting more pleasure out of my movie-viewing.

I thought I could work on this on my own by trying to write a short review of every movie I watch in 2017 on my Letterboxd profile, and eventually all of that would somehow lead to me getting better at it, but it's not going great. I'm not happy with what I'm producing, and for a lot of the movies I see I can't think of much to say beyond, "It was fine I guess?" And then trying to streeetttccch that out to at least something resembling a paragraph feels torturous.

Are there any good books or websites you could recommend to help improve my film thinking/writing?