(Beginner) Study Fallacies. If you memorize enough fallacies, you’ll start hearing people make them all the time in arguments. You’ll experience a similar effect with #3 (LSAT). It only takes a few minutes to read the list and start spotting them. Pay special attention to red herrings, appeals to authority, straw man, anecdotal evidence, and ad homonym attacks.
(Beginner) Do your research. Know your argument’s strengths and weaknesses. Know your opponent’s. Most arguments are won by the person who is best prepared, not the person who is right.
(Advanced) Study the LSAT logical reasoning section. If you take enough logical reasoning sections, you start to hear flaws in arguments all over the place.
Read The Tools of Argument – how the best lawyers think, argue, and win by Trachtman. This might be the best book on arguing that I’ve seen. It goes into depth on the different types of arguments you can make in response to a case. It is very oriented to the legal profession, but somehow manages to be applicable in regular conversation.
Get good at using questions to gather information. Read any book on depositions. Deposition Questioning Strategies & Techniques by Bergman is a great one to start with. Depositions are legal tools for building leverage. Lawyers and clients sit down and ask questions the other side has to answer. The information gathered becomes very useful to both sides for discrediting, arguing, and avoiding weak positions. Once you’ve studied these strategies, start practicing asking questions that discredit and drag information out of your opponents.
Practice counter arguing and playing devil’s advocate. Make a list of positions that are common in your social circle. Now research the opposing side’s arguments. Practice playing devil’s advocate – but don’t be surprised when people get annoyed with you. An easy way to practice with out making everyone angry is to frame the objection or counter point as a question. “So what would you say to someone who argued that X?”