Catholic Voting Guide from the National Catholic Register
I have been looking for a while for a good impartial voting guide that both lays out Catholic principles for informing oneself before deciding how to vote and explains some of the complex principles for voters to understand how to weigh issues against each other, what is and isn't negotiable, and so on. All while not endorsing a candidate or a party explicitly or implicitly.
I finally found a good one, from the always-worth-reading Catholic newspaper, the National Catholic Register. It explains candidate and party positions in light of Catholic teaching, rather than partisan politics.
The guide consists mostly of direct quotes from candidates and the major political party platforms, without analysis. (That's your task, as a Catholic voter).
The issues listed are not the only issues that you might choose to weigh, so you may have to do additional research on your own, but they cover many important areas of concern to the Christian voter.
You might want to "bookmark" the N.C. Register's website and come back to it each election season.