I found myself in a similar situation about year and a half ago wanting to learn recommender systems. What worked best for me was the already mentioned coursera

I found myself in a similar situation about year and a half ago wanting to learn recommender systems. What worked best for me was the already mentioned coursera recommender system course. Then if you can, go to RecSys conference (this year happening in fall in Boston). Then the absolute go to book for recommender systems is "Recommender systems handbook" - it has second edition that came out last year and this book covers everything from math, practical issues/architecture, to industry use cases etc. Good luck!