The Very Short Teach Yourself Logic Guide

"The full TYL Study Guide is a hundred page PDF. That’s full of good things, including detailed descriptions of lots of books, including alternative suggestions to the top recommendations. But some readers may just want the unvarnished headline news. So here, excerpted from the current version of the full Guide, is a one-webpage mini-guide to some particularly good entry-level reading on the standard core mathematical logic curriculum (a step up from baby logic)...."

http://www.logicmatters.net/tyl/shorter-tyl/