Give yourself a short organizing pause before speaking. Start with the answer or the two main points you want to make, then explain the detail underneath them.

You do not need a perfect structure in your head before the first word. A simple top-down sentence such as 'I see two things to consider' can create the structure while you are speaking.

Practice taking ten or fifteen seconds to organize common brainstorming and judgment questions instead of answering immediately. If useful, this guide on structured communication in case interviews gives more detail.