Advice on improving debate skills

Hello and greetings, I’ve seen in all sorts of debates that you’ve participated in that while the person in front of you in the debate presents his position, you make notes for yourself on the page. What do you usually write there? I want to know because I’m interested in learning from your debate skills, how do you know how to capture the problematic arguments and attack the bull by the horns when the person in front of you in the debate presents a lot of arguments over a long period of time? thanks.