Kellstedt and Whitten Chap. 8
Important takeways:
Using cross-tabs is a great way to eliminate ideas; once in a great while you can get an idea from them, but if you're using the cross-tabs to derive your theory, you're doing it backwards. Instead, you use the theory to lead you to cross-tabs that tell you if there's anything worth pursuing.
OLS regression is remarkably powerful.
It tells you the direction of the relationship, the strength, and the statistical significance.