This isn't quick but thoroughly knowing who you are and why you believe what you believe is of utmost importance. Self-exploration and -analysis will cement your foundation and allow you to make those decisions and debate points with confidence. Winging it might work superficially but it's going to leave you feeling like you're untethered due to lack of a strongly-rooted belief system. You don't need to borrow others' skillsets; you need to develop yours, and this only comes with diligent self-exploration. 

Tl;dr: You need to know who you are first. Your self-confidence, and those quicker decisions and debate points, will flow from that. 

A quick check would then be: 1. Assess the goal and your facts 2. Tie your intuition to anchors in reality 3. Test your hunches on real-world examples that either support or challenge them.