Also some good resources in this Quora: https://www.quora.com/What-are-the-best-resources-to-learn-q...
And if your interest is in the k language more than kdb+/q, then I have found the docs in John Earnest's ('RodgerTheGreat) oK interpreter a succinct, example-focused introduction: https://github.com/JohnEarnest/ok/blob/gh-pages/docs/Manual.... Plus using his browser-based REPL (http://johnearnest.github.io/ok/index.html) may lower the barriers to entry, and iKe (http://johnearnest.github.io/ok/ike/ike.html) is great for experimentation...http://johnearnest.github.io/ok/ike/ike.html?gist=9c5f43baa4...