I spoke with my spiritual director and he told me that my top spiritual priority right now is to find out what the Church teach teaches. That way I will be able to repent of any heresies that I may or may not have fallen into, and be forgiven.
He said that to do this, I should systematically go through the Catechism and make sure I understand it all. He suggested I use the Baltimore Catechism #3, but he also said the Catechism of Trent would work, or any good catechism really.
What I personally would like to do is to use the oldest/earliest catechisms available, and perhaps compare them with the stuff in the newer catechisms (Baltimore and Trent), in order ultimately to determine whether the Catholic Church is in fact the true Church. I want to see that teachings such as magisterial infallibility, papal supremacy, etc., do in fact date back to the very beginning. I want to see that the most ancient Christians believed in the filoque and in the immaculate conception, and in all the other stuff that the Catholic Church has later declared as dogmatic. (Magisterial infallibility would be the big one, since it holds everything else together.)
Ideally, I'm looking for any catechisms from the first or second century. Not sure if any exist though. I could start with Scripture I guess, but Scripture isn't all that concise (not to mention it's so obscure that many who read it fall into heresy). There is also the Didache which contains some data, but it's more practical than catechetical, and it's quite limited in scope. I'm looking for something more along the lines of an actual catechism. St. Augustine's Enchiridion comes close, but that's not going to work for my purposes, as I suspect that St. Augustine and his teachers are part of the problem. (I want something that hasn't been tainted by Neoplatonistic thought.)