When I was in junior high, my Campfire Leader taught me to crochet granny squares. I went right out and bought some yarn and was determined to follow the pattern on the paper yarn wrapper to make a pair of slippers for my Mom for Christmas. But I had no idea how to read the pattern.
I found a list of abbreviations in the back of a crochet book, and have distinct memories of flipping back and forth to figure out what the abbreviations meant and how to do the stitches until I finally learned most of them. And so, I taught myself to read those crazy patterns.
But you do not have to do it all by yourself. I frequently have people tell me they know how to crochet but they cannot read patterns. When I am teaching crochet classes I always give my students a "cheat sheet" with abbreviations, written directions, and diagrams for all of the basic crochet stitches. These days, all of this information can be found online at various sites.
Here are just a few of my favorites:
Crochet Guild Of America - Lessons for Righthanders and Lefthanders
Craft Yarn Council - Full List of Abbreviations and much more
Stitch Divas - Clear pictures and explanations of stitches
Free Vintage Crochet - Diagrams and Videos for each stitch