Operating in the midst your own ignorance is a critical skill for junior associates. In situations where you are communicating directly with a client and have no idea what to tell them, one simple tactic is to advise that "there are several approaches" and that you will "revert back" with the one that is “most tax efficient” as you don't want to waste the client's valuable time walking through multiple scenarios. This gambit will usually succeed in buying you enough time to figure out a plausible answer. Some may ask, “But what do I do if they want to talk about the different approaches?” You then have two options: (1) claim technical difficulties with your phone or (2) start coughing uncontrollably.