You should develop your own shorthand so that you can more quickly and easily take notes. No one else has to understand your notes except you. For example, instead of writing "energy", you may write "nrg". To everyone else that might not make sense, but as long as you remember your short hand, you'll be good.
You should also leave small words out of sentences. For example in the sentence: "The energy increases with the amount of sunlight." I would write this note: "Nrg (up arrow) w/sun." I can't draw an arrow in here, but I hope that you get the point.