Do not take up too much time and space just describing what Singer and his critics have said ?
Make sure that at the level of every section/paragraph has got an argument which is yours and you are using your voice and your reasoning to make an argument about the material that is in that section or paragraph. ?
The exception may be at the very beginning of the essay, that is fundamental but except that other than explaining Singer each paragraph has to make some argument in that paragraph. ?
That extends the level of the section. Each paragraph is then used to build a section which will also have an argument and that argument is going to be your argument.