I honestly don’t know much about what intro texts are out there. I read What Does It All Mean? by Thomas Nagel in an intro class; it’s very short and to the point. Various people on the internet also recommend Think: A Compelling Introduction to Philosophy by Simon Blackburn.
For information on specific topics, I find the Stanford Encyclopedia of Philosophy (plato.stanford.edu) very helpful. Sometimes it can get pretty technical, though; the articles seem to be geared toward students who already have some background in philosophy and are exploring a new subfield.