In your evaluation there are two areas that you must cover: content and delivery. Some people like to start with a blank sheet and take notes as the speech progresses. Others prepare categories and then jot down triggers in the appropriate area.
I think it is a bit difficult to start with a total blank page as well as jotting things down in predefined boxes because it shuts down my creativity.
I listened to one woman doing a great evaluation, she won everything so I walked up to her afterwards and asked her how she did it. She told me “Oh I just right down things I like and things I don’t like and build from there…” It’s a simple strategy that obviously works well enough to win an evaluation contest. I developed my own way to take notes. I do it in a mindmap. In the middle I write the title or name of the speaker. Then I start at one o’clock and fill out what I hear in the speech. I might write introduction, Personal Story, and plus next to it. And then I try to map the speech by putting pluses and minuses as I go along, or right after the speech.
I think a good way to find out what balance works for you is to try the different approaches and assess your own evaluations.
(1) Blank sheet of paper
(2) Predefined boxes
I learnt to improve my evaluations by observing others and including what I liked into my own repertoire. A good idea is to note down effective evaluation tips from others.